I have managed to install Ubuntu Touch onto my Redmi note 7. It requires you to be patient and persevere, so I will give a few points from my experience.

Kudos to the installer, it makes life so easy, but being in beta it has its flaws. The main flaw across the phones and tablets I have installed to, is the phone or tablet always reboots during the download phase of Ubuntu Touch which causes the install to fail. When it does this, persevere and start again - it will work, especially on this phone.
I have now flashed this phone a few times, to make it work (on both phones in my possession) make sure a working SIM is installed - don't know why, but it worked for me, without it it always hung at waiting for adb device.
I flashed the phones with Android 10 installed and it worked. I did follow the advice and down graded to Android 9, but without the working SIM, it failed.
The other thing I found I had to do, apart from when unlocking is to register it with my Xiaomi account. I don't know again if this had much bearing, but when not registered it failed to install Ubuntu Touch.
Be patient. It seems to hang a lot, but will get there. The initial firmware flash, sits there for about five minutes with the progress bar 75% across the computer screen (all you get on the phone is the fastboot logo). It will then reboot and you don't see it get to 100%.
You know you are going to have success with the flash when it sits at the Halium-9 recovery and the installer is pushing the files to the phone.

I am very pleased to get this working and would like to thank all for porting this and the advice and notices given in this forum, especially Stanwood who linked to a very useful instruction on Github. So a big thanks from me, now I have a "premium" phone to run as a daily driver with Ubuntu touch.

Try using the latest version of Android tools, and open the terminal in the platform-tools folder (with Windows). I have had issues with older versions of fastboot and adb.

Also try

fastboot flashing unlock_critical

Before you buy download and run the Ubuntu Touch installer as though you are going to flash your phone. There is extra steps you need to know with this phone:

Don't worry about the screen, we are on OTA-19 now.

Hi all, I have received another nexus 6p to try and followed all the steps, but this time in Ubuntu 20.04.1. Worked straight off, so thank you for all your help. I have noticed the installer has updated to 0.5.5-beta. (I am using the Stable release). Thanks again and keep up the good work.

I had the same issue on one oneplus one I have (it would hang or always boot to recovery). I installed TWRP and formatted and wiped all partitions. I then installed the latest version of OxygenOS for that phone (codename of phone is bacon). Installed Ubuntu touch with no issues after that.

Re: Porting to OnePlus One A0001 Cyanogen - rather than necrotising an old thread, I thought I would pass on my experience. I have flashed a couple of A0001's and they have both been absolutely straightforward and fine to do, but this 64Gb Slate Gray was a different animal, but I am not one to give up! It was always not detected as an OPO, but as its camera MSM8974, so I must assume the hardware has changed slightly between the same makes over time. Anyway have followed the the above mentioned older thread (reinstalled Android a few times) and finally got a successful install. The previous errors, were always the install would stop, the phone would not reboot, but the bootloader screen would appear over the top of the install screen and that would be it, start again.. So, the steps that worked for me:

Install the latest (last) version of Cyanogen
Force the camera to stop
usual, USB debugging etc as described
Boot into Fastboot, unlock the bootloader and MAKE SURE IT IS done with

./fasboot oem device-info

This should show device tampered: true and device unlocked: true. Anything with false on those two lines the unlock has failed.

Then using the installer follow the instructions and make sure you switch the phone off before starting boot back into fastboot, likewise when you go into recovery. It should work from there.

Done with Windows 10 ( no joy on Ubuntu)
Ubports installer 0.8.8-beta
Samsung USB cable
USB 3.0 from the back of a PC.

I thought I would share this as I have spent a few hours working this out (thank you Android install) and it may help others.

Edit: Forgot to add, ensure the phone is charged to at least 95%.

Hi thanks for the reply. Unfortunately I am a "weekend warrior", work commitments leave me with little time to tinker with it, but when I get some at weekends , I will try again. I have now some non fully working phones to test (bad motherboards etc) against and I will try another version of TWRP (I tried the latest) to see if that works better. I am just hoping it is not coincidence and either the RAM or (not CPU) eMMC has failed (I have access to a reflow machine, but with COVID I don't know when. Thanks for all your suggestions, when I have some spare cash I will start donating to UBports as I think it is a really worthwhile cause, anything to stop hardware going into a rubbish tip.

@digital_wookiee Great stuff. As a side note, you don't need to root the phone to run TRWP. It is a very handy phone recovery tool and more.

Have you ensured you are on Oxygen OS 9.0?
Have you enabled USB debugging and (if available I don't have this phone) OEM unlock in Developer Options and rebooted the phone?
Have you Unlocked the Bootloader and rebooted to the bootloader? This has to be done or the install won't work and error very quickly.
Have you installed compatible TWRP and ensured all the partitions are formatted to EXT4?
If it fails on the Windows 10 installer, try the installer on another operating system such as Ubuntu, Debian, Manjaro etc.

Leave it, it should take anywhere from 5 minutes to around 20 minutes. It seems slow, if it goes beyond, start the process again, but don't tick wipe (or if the Installer says "Start as new a new install") format etc. My galaxy Note 4 took what seem like forever, stuck at the initial boot screen, but then all went well.

@bigmouth Good one, saved a lot of time by the looks of things. If that is the case what I suggested would not have worked at all if the original config file is flawed.

@phandersson Check this out.

@phandersson You do not need to root the phone. You need to be on Android 9 and not 8 to flash Ubuntu Touch. You have to follow the steps precisely with Xiaomi phones to unlock the bootloader, which involves:
1)having a working SIM card inserted
2)creating a MI account and linking the phone to it
3) setting up developer mode
4) in developer mode setting OEM unlock to on and enabling USB debugging
5)unlock the phone using the Mi unlock tool and not fastboot OEM unlock.

Then be patient and go back into Android and re-enable USB debugging and power the phone off. Then power back on and enter flashboot mode by holding the power on and volume down button. In flashboot mode, flash the latest version of TWRP for that phone and wipe and format the partitions to EXT 4. Reboot to fastboot mode and Ubuntu Touch should install.

@bigmouth It could be worthwhile starting from scratch (a pain I know), but put Android back on and trying again. If the phone picked up the SIM under the previous installed Android version, the phone should be working fine and Ubuntu touch is the issue. Go back to Android 9 (whatever Xiaomi like to call it!) from here at around page 9~10 and use the fastboot global image that gives you Android 9.0. Then go through the steps again to install Ubuntu Touch. It looks like only the developer channel is available for this phone at this moment.

@bigmouth Ok, that has eliminated that. If it is still on the development channel the issue could lie there. The version of Android the phone was on has some bearing , was it Android 9? ( I have spent many hours reinstalling Android to roll it back and then getting Ubuntu touch to install).

@homer No, I am on the stable channel. All has been fine with most phones.

@bigmouth Ok, That worked for me on one of my phones, try reinstalling with a wipe that may remove the issue.

Have you tried removing the SIM and reinstalling Ubuntu Touch (without ticking the wipe data etc boxes)?

@swomp You have to be on the Xiaomi stock android. The Problem with some ROMs is that they resize partitions which causes issues with Ubuntu touch.

Hi, check this post of mine out. I would make sure you are on Android 9 or 10 and be very patient.