@Flohack @atomos SUCCESS!

After trying multiple times using the Macbook air ports. I tried a different setup. Used an external USB/USB C dock (Dell Universal Dock D6000) with a USB C to USB C cable connected to the phone.

So Macbook Air (2013) -> Dell Universal Dock -> Pixel 2 XL.

And when trying the script it finally worked!

~/Desktop/ubports/halium-install$ ./halium-install-standalone.sh -p ut -s ubuntu-touch-android9-arm64.tar.gz system.img 
[sudo] password for :      
D: Chosen rootfs is ubuntu-touch-android9-arm64.tar.gz
D: Chosen android image is system.img
D: Chosen release is ut
D: Compress images before pushing: false

I: Writing rootfs into mountable image
I: Writing android image into mountable image
I: Running post installation tasks
enabling SSH ... [done]
Please enter a new password for the user 'phablet':
Enter new UNIX password: 
Retype new UNIX password: 
passwd: password updated successfully
I: Shrinking images
e2fsck 1.45.5 (07-Jan-2020)
resize2fs 1.45.5 (07-Jan-2020)
Resizing the filesystem on .halium-install-imgs.Yy132/system.img to 231448 (4k) blocks.
Begin pass 3 (max = 20)
Scanning inode table          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The filesystem on .halium-install-imgs.Yy132/system.img is now 231448 (4k) blocks long.

I: Unmounting images
I: Pushing rootfs and android image to /data via ADB
I:    Pushing rootfs to /data via ADB
.halium-install-imgs.Yy132/rootfs.img:....0 MB/s (3221225472 bytes in 109.898s)
I:    Pushing android image to /data via ADB
.halium-install-imgs.Yy132/system.img:...27.5 MB/s (948011008 bytes in 32.918s)
I:    Renaming to system-as-root compatible system image

real	2m22.986s
user	0m0.438s
sys	0m6.972s
I: Cleaning up
umount: .halium-install-rootfs.5pR4w: not mounted.

Now on to testing capabilities. Thanks for all your help and input. @Flohack recommendation to try different host ports helped!

@flohack I can confirm no audio on whole device.

@Flohack @atomos SUCCESS!

After trying multiple times using the Macbook air ports. I tried a different setup. Used an external USB/USB C dock (Dell Universal Dock D6000) with a USB C to USB C cable connected to the phone.

So Macbook Air (2013) -> Dell Universal Dock -> Pixel 2 XL.

And when trying the script it finally worked!

~/Desktop/ubports/halium-install$ ./halium-install-standalone.sh -p ut -s ubuntu-touch-android9-arm64.tar.gz system.img 
[sudo] password for :      
D: Chosen rootfs is ubuntu-touch-android9-arm64.tar.gz
D: Chosen android image is system.img
D: Chosen release is ut
D: Compress images before pushing: false

I: Writing rootfs into mountable image
I: Writing android image into mountable image
I: Running post installation tasks
enabling SSH ... [done]
Please enter a new password for the user 'phablet':
Enter new UNIX password: 
Retype new UNIX password: 
passwd: password updated successfully
I: Shrinking images
e2fsck 1.45.5 (07-Jan-2020)
resize2fs 1.45.5 (07-Jan-2020)
Resizing the filesystem on .halium-install-imgs.Yy132/system.img to 231448 (4k) blocks.
Begin pass 3 (max = 20)
Scanning inode table          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The filesystem on .halium-install-imgs.Yy132/system.img is now 231448 (4k) blocks long.

I: Unmounting images
I: Pushing rootfs and android image to /data via ADB
I:    Pushing rootfs to /data via ADB
.halium-install-imgs.Yy132/rootfs.img:....0 MB/s (3221225472 bytes in 109.898s)
I:    Pushing android image to /data via ADB
.halium-install-imgs.Yy132/system.img:...27.5 MB/s (948011008 bytes in 32.918s)
I:    Renaming to system-as-root compatible system image

real	2m22.986s
user	0m0.438s
sys	0m6.972s
I: Cleaning up
umount: .halium-install-rootfs.5pR4w: not mounted.

Now on to testing capabilities. Thanks for all your help and input. @Flohack recommendation to try different host ports helped!

@atomos Yes, same issue. Also tried a different port and several USB C cables.

~/Desktop/ubports/halium-install$ ./halium-install-standalone.sh -p ut -s ubuntu-touch-android9-arm64.tar.gz system.img 
[sudo] password for :      
D: Chosen rootfs is ubuntu-touch-android9-arm64.tar.gz
D: Chosen android image is system.img
D: Chosen release is ut
D: Compress images before pushing: false

I: Writing rootfs into mountable image
I: Writing android image into mountable image
I: Running post installation tasks
enabling SSH ... [done]
Please enter a new password for the user 'phablet':
Enter new UNIX password: 
Retype new UNIX password: 
passwd: password updated successfully
I: Shrinking images
e2fsck 1.45.5 (07-Jan-2020)
resize2fs 1.45.5 (07-Jan-2020)
Resizing the filesystem on .halium-install-imgs.0eqim/system.img to 231448 (4k) blocks.
Begin pass 3 (max = 20)
Scanning inode table          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The filesystem on .halium-install-imgs.0eqim/system.img is now 231448 (4k) blocks long.

I: Unmounting images
I: Pushing rootfs and android image to /data via ADB
I:    Pushing rootfs to /data via ADB
* daemon not running; starting now at tcp:5037
* daemon started successfully
adb: error: 65544-byte write failed: Success
I:    Pushing android image to /data via ADB
adb: error: failed to get feature set: device offline
I:    Renaming to system-as-root compatible system image
adb: device offline

real	0m6.220s
user	0m0.025s
sys	0m0.721s
Error: Couldn't copy the files to the device, is it connected?
I: Cleaning up
umount: .halium-install-rootfs.o87p7: not mounted.
adb: device offline

Second attempt:

~/Desktop/ubports/halium-install$ ./halium-install-standalone.sh -p ut -s ubuntu-touch-android9-arm64.tar.gz system.img 
D: Chosen rootfs is ubuntu-touch-android9-arm64.tar.gz
D: Chosen android image is system.img
D: Chosen release is ut
D: Compress images before pushing: false

I: Writing rootfs into mountable image
I: Writing android image into mountable image
I: Running post installation tasks
enabling SSH ... [done]
Please enter a new password for the user 'phablet':
Enter new UNIX password: 
Retype new UNIX password: 
passwd: password updated successfully
I: Shrinking images
e2fsck 1.45.5 (07-Jan-2020)
resize2fs 1.45.5 (07-Jan-2020)
Resizing the filesystem on .halium-install-imgs.zPBDe/system.img to 231448 (4k) blocks.
Begin pass 3 (max = 20)
Scanning inode table          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The filesystem on .halium-install-imgs.zPBDe/system.img is now 231448 (4k) blocks long.

I: Unmounting images
I: Pushing rootfs and android image to /data via ADB
I:    Pushing rootfs to /data via ADB
adb: error: 65544-byte write failed: Success
I:    Pushing android image to /data via ADB
adb: error: failed to read copy response
.halium-install-imgs.zPBDe/system.img:...157.2 MB/s (948011008 bytes in 5.750s)
adb: error: failed to read copy response
I:    Renaming to system-as-root compatible system image
adb: no devices/emulators found

real	0m12.006s
user	0m0.043s
sys	0m1.377s
Error: Couldn't copy the files to the device, is it connected?
I: Cleaning up
umount: .halium-install-rootfs.ZVxrz: not mounted.

Did some more tests. Was looking at the wrong string, it looks like adb push does work.

~/Desktop/ubports/halium-install$ cp ubuntu-touch-android9-arm64.tar.gz ubutuarchiverenamed

~/Desktop/ubports/halium-install$ adb push ubutuarchiverenamed /data
adb: error: failed to read copy response
ubutuarchiverenamed: 1 file pushed, 0 ...108.0 MB/s (616134854 bytes in 5.438s)
adb: error: failed to read copy response

~/Desktop/ubports/halium-install$ adb push ubuntu-touch-android9-arm64.tar.gz /data
adb: error: failed to read copy response.tar.gz
ubuntu-touch-android9-arm64.tar.gz: 1 ...102.3 MB/s (616134854 bytes in 5.741s)
adb: error: failed to read copy response


~/Desktop/ubports/halium-install$ adb push system.img /data
adb: error: failed to read copy response
system.img: 1 file pushed, 0 skipped. 63.1 MB/s (365404512 bytes in 5.520s)
adb: error: failed to read copy response

~/Desktop/ubports/halium-install$ adb push twrp-3.5.0_9-0-taimen.img /data
adb: error: failed to read copy response
twrp-3.5.0_9-0-taimen.img: 1 file push...d. 7.8 MB/s (41943040 bytes in 5.136s)
adb: error: failed to read copy response

~/Desktop/ubports/halium-install$ adb push vendor.img /data
adb: error: failed to read copy response
vendor.img: 1 file pushed, 0 skipped. 64.2 MB/s (363557072 bytes in 5.404s)
adb: error: failed to read copy response

I also tried to use the install script without the password and user parameters which allows the system image to push, but it fails pushing the rootfs :

~/Desktop/ubports/halium-install$ sudo ./halium-install-standalone.sh ubuntu-touch-android9-arm64.tar.gz system.img 
D: Chosen rootfs is ubuntu-touch-android9-arm64.tar.gz
D: Chosen android image is system.img
D: Chosen release is none
D: Compress images before pushing: false

I: Writing rootfs into mountable image
I: Writing android image into mountable image
I: Running post installation tasks
I: Shrinking images
e2fsck 1.45.5 (07-Jan-2020)
resize2fs 1.45.5 (07-Jan-2020)
Resizing the filesystem on .halium-install-imgs.uXTvp/system.img to 231448 (4k) blocks.
Begin pass 3 (max = 20)
Scanning inode table          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The filesystem on .halium-install-imgs.uXTvp/system.img is now 231448 (4k) blocks long.

I: Unmounting images
I: Pushing rootfs and android image to /data via ADB
I:    Pushing rootfs to /data via ADB
adb: error: 65544-byte write failed: Success
I:    Pushing android image to /data via ADB
adb: error: failed to read copy response
.halium-install-imgs.uXTvp/system.img:...147.9 MB/s (948011008 bytes in 6.112s)
adb: error: failed to read copy response

real	0m12.719s
user	0m0.045s
sys	0m1.496s
I: Cleaning up
umount: .halium-install-rootfs.Hcs48: not mounted.

But if I try to use the script using "-P" or "-S" I get the following:

~/Desktop/ubports/halium-install$ sudo ./halium-install-standalone.sh -p ut -s ubuntu-touch-android9-arm64.tar.gz system.img 
D: Chosen rootfs is ubuntu-touch-android9-arm64.tar.gz
D: Chosen android image is system.img
D: Chosen release is ut
D: Compress images before pushing: false

I: Writing rootfs into mountable image
I: Writing android image into mountable image
I: Running post installation tasks
enabling SSH ... [done]
Please enter a new password for the user 'phablet':
Enter new UNIX password: 
Retype new UNIX password: 
passwd: password updated successfully
I: Shrinking images
e2fsck 1.45.5 (07-Jan-2020)
resize2fs 1.45.5 (07-Jan-2020)
Resizing the filesystem on .halium-install-imgs.V34FH/system.img to 231448 (4k) blocks.
Begin pass 3 (max = 20)
Scanning inode table          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The filesystem on .halium-install-imgs.V34FH/system.img is now 231448 (4k) blocks long.

I: Unmounting images
I: Pushing rootfs and android image to /data via ADB
I:    Pushing rootfs to /data via ADB
adb: error: failed to get feature set: device offline
I:    Pushing android image to /data via ADB
adb: error: failed to get feature set: device offline
I:    Renaming to system-as-root compatible system image
adb: device offline

real	0m0.016s
user	0m0.008s
sys	0m0.005s
Error: Couldn't copy the files to the device, is it connected?
I: Cleaning up
umount: .halium-install-rootfs.mFbra: not mounted.
adb: device offline

~/Desktop/ubports/halium-install$ sudo ./halium-install-standalone.sh -p ut -s ubuntu-touch-android9-arm64.tar.gz system.img 
D: Chosen rootfs is ubuntu-touch-android9-arm64.tar.gz
D: Chosen android image is system.img
D: Chosen release is ut
D: Compress images before pushing: false

I: Writing rootfs into mountable image
I: Writing android image into mountable image
I: Running post installation tasks
enabling SSH ... [done]
Please enter a new password for the user 'phablet':
Enter new UNIX password: 
Retype new UNIX password: 
passwd: password updated successfully

I: Shrinking images
e2fsck 1.45.5 (07-Jan-2020)
resize2fs 1.45.5 (07-Jan-2020)
Resizing the filesystem on .halium-install-imgs.2YQgD/system.img to 231448 (4k) blocks.
Begin pass 3 (max = 20)
Scanning inode table          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The filesystem on .halium-install-imgs.2YQgD/system.img is now 231448 (4k) blocks long.

I: Unmounting images
I: Pushing rootfs and android image to /data via ADB
I:    Pushing rootfs to /data via ADB
adb: error: 65544-byte write failed: Success
I:    Pushing android image to /data via ADB
adb: error: failed to get feature set: device offline
I:    Renaming to system-as-root compatible system image
adb: device offline

real	0m6.227s
user	0m0.019s
sys	0m0.715s
Error: Couldn't copy the files to the device, is it connected?
I: Cleaning up
umount: .halium-install-rootfs.dqGZa: not mounted.
adb: device offline

Testing using TWRP 3.2.3.0 (fails at 100mb)

~/Desktop/ubports/halium-install$ fastboot boot twrp-3.2.3-0-taimen.img 
Sending 'boot.img' (40960 KB)                      OKAY [  1.187s]
Booting                                            OKAY [  0.001s]
Finished. Total time: 1.313s

~/Desktop/ubports/halium-install$ adb push ubuntu-touch-android9-arm64.tar.gz /data
adb: error: failed to read copy response.tar.gz
ubuntu-touch-android9-arm64.tar.gz: 1 ...109.3 MB/s (616134854 bytes in 5.378s)
adb: error: failed to read copy response

~/Desktop/ubports/halium-install$ adb push ubuntu-touch-android9-arm64.tar.gz /data
adb: error: failed to read copy response.tar.gz
ubuntu-touch-android9-arm64.tar.gz: 1 ...109.9 MB/s (616134854 bytes in 5.348s)
adb: error: failed to read copy response

~/Desktop/ubports/halium-install$ adb push ubuntu-touch-android9-arm64.tar.gz /data
adb: error: failed to read copy response.tar.gz
ubuntu-touch-android9-arm64.tar.gz: 1 ...108.1 MB/s (616134854 bytes in 5.436s)
adb: error: failed to read copy response

Testing using TWRP 3.2.3.1 (fails at 100mb)

~/Desktop/ubports/halium-install$ fastboot boot twrp-3.2.3-1-taimen.img 
Sending 'boot.img' (40960 KB)                      OKAY [  1.209s]
Booting                                            OKAY [  0.001s]
Finished. Total time: 1.310s

~/Desktop/ubports/halium-install$ adb push ubuntu-touch-android9-arm64.tar.gz /data
adb: error: failed to read copy response.tar.gz
ubuntu-touch-android9-arm64.tar.gz: 1 ...110.1 MB/s (616134854 bytes in 5.336s)
adb: error: failed to read copy response

~/Desktop/ubports/halium-install$ sudo adb push ubuntu-touch-android9-arm64.tar.gz /data

[sudo] password for  :      

adb: error: failed to read copy response.tar.gz
ubuntu-touch-android9-arm64.tar.gz: 1 ...109.8 MB/s (616134854 bytes in 5.350s)
adb: error: failed to read copy response

Testing using TWRP 3.5.0.9 (Does not upload, frozen at 0%)

~/Desktop/ubports/halium-install$ adb push ubuntu-touch-android9-arm64.tar.gz /data
[  0%] /data/ubuntu-touch-android9-arm64.tar.gz

~/Desktop/ubports/halium-install$ adb push ubuntu-touch-android9-arm64.tar.gz /data

adb F 02-04 11:28:55 40783 40783 file_sync_client.cpp:473] protocol fault: failed to read stat response: Success
Aborted (core dumped)

@flohack just tried adb push using TWRP 3.2.3.0, seems that the push is failing around 100mb.

~/Desktop/ubports/halium-install$ adb push ubuntu-touch-android9-arm64.tar.gz /data
adb: error: failed to get feature set: device offline

~/Desktop/ubports/halium-install$ adb push ubuntu-touch-android9-arm64.tar.gz /data
adb: error: failed to read copy response.tar.gz
ubuntu-touch-android9-arm64.tar.gz: 1 ... 97.2 MB/s (616134854 bytes in 6.048s)
adb: error: failed to read copy response

~/Desktop/ubports/halium-install$ adb push ubuntu-touch-android9-arm64.tar.gz /data
adb: error: failed to read copy response.tar.gz
ubuntu-touch-android9-arm64.tar.gz: 1 ...103.4 MB/s (616134854 bytes in 5.684s)
adb: error: failed to read copy response

~/Desktop/ubports/halium-install$ adb push ubuntu-touch-android9-arm64.tar.gz /data
adb: error: failed to read copy response.tar.gz
ubuntu-touch-android9-arm64.tar.gz: 1 ...109.3 MB/s (616134854 bytes in 5.376s)
adb: error: failed to read copy response

~/Desktop/ubports/halium-install$ adb push ubuntu-touch-android9-arm64.tar.gz /data
[  1%] /data/ubuntu-touch-android9-arm64.tar.gz
adb: error: failed to read copy response.tar.gz
ubuntu-touch-android9-arm64.tar.gz: 1 ...108.5 MB/s (616134854 bytes in 5.418s)
adb: error: failed to read copy response

~/Desktop/ubports/halium-install$ adb push ubuntu-touch-android9-arm64.tar.gz /data
adb: error: failed to get feature set: device offline
~/Desktop/ubports/halium-install$ 

Just ran into an issue rolling back. Will have to pick this test up later this week. Thanks for everyone's help.

@atomos ok will try that out and report back. Thanks for the help : )

@atomos could the issue on mine might be that I have to roll back to android 9 before trying the steps?

For example should I be rolling back to 9.0.0 (PPR1.180610.009, Aug 2018) from https://developers.google.com/android/images ?

Trying an earlier version of TWRP 3.2.3-1:

~/Desktop/ubports/halium-install$ sudo ./halium-install-standalone.sh -p ut -s ubuntu-touch-android9-arm64.tar.gz.1 system.img 
D: Chosen rootfs is ubuntu-touch-android9-arm64.tar.gz.1
D: Chosen android image is system.img
D: Chosen release is ut
D: Compress images before pushing: false

I: Writing rootfs into mountable image
I: Writing android image into mountable image
I: Running post installation tasks
enabling SSH ... [done]
Please enter a new password for the user 'phablet':
Enter new UNIX password: 
Retype new UNIX password: 
passwd: password updated successfully
I: Shrinking images
e2fsck 1.45.5 (07-Jan-2020)
resize2fs 1.45.5 (07-Jan-2020)
Resizing the filesystem on .halium-install-imgs.OTiWz/system.img to 231448 (4k) blocks.
Begin pass 3 (max = 20)
Scanning inode table          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The filesystem on .halium-install-imgs.OTiWz/system.img is now 231448 (4k) blocks long.

I: Unmounting images
I: Pushing rootfs and android image to /data via ADB
I:    Pushing rootfs to /data via ADB
[  0%] /data/rootfs.img
[  6%] /data/rootfs.img
adb: error: 65544-byte write failed: Success

I:    Pushing android image to /data via ADB
[  0%] /data/system.img
[ 82%] /data/system.img
adb: error: failed to read copy response
.halium-install-imgs.OTiWz/system.img: 1 file...ipped. 159.6 MB/s (948011008 bytes in 5.665s)
adb: error: failed to read copy response
I:    Renaming to system-as-root compatible system image

Then adb freezes and screen remains unresponsive.