@whomreally I don't know how to post this but I solved my issue, sometimes asking the question makes you find the answer! Hope this can help people:
Thinking this is an issue of fastboot not recognizing the tablet, I went on my S20 PC Windows 10 and followed this advice https://forum.fairphone.com/t/fp3-how-to-solve-non-recognized-fp3-device-in-fastboot-on-a-win10-device-easy-e-os-installer/68674/15. Since I had previously connected my tablet before, with it disconnected I went to device manager>view>show hidden devices and there was something like other devices. I went to update driver>update driver from windows update and there it took me to Windows updates in settings and I saw optional drivers and installed both of those (something like android and fastboot). I also read this (https://forum.fairphone.com/t/problem-to-unlock-device-state-with-fastboot-command/69113/2) then installed the https://developer.android.com/studio/releases/platform-tools and added the path to the environment variables. I opened the tablet in fastboot by pressing volume up and power while closed, then in recovery chose boot into bootloader. I plugged the tablet to PC, ran cmd as admin, ran adb devices that started but listed no devices. Then I ran fastboot devices and it listed my tablet. I opened ubports-installer (not as admin), chose device manually and followed instructions and files pushed to the device in recovery mode. It then rebooted into ubuntu logo, then was turning and eventually I had Ubuntu Touch up and running.

@whomreally I don't know how to post this but I solved my issue, sometimes asking the question makes you find the answer! Hope this can help people:
Thinking this is an issue of fastboot not recognizing the tablet, I went on my S20 PC Windows 10 and followed this advice https://forum.fairphone.com/t/fp3-how-to-solve-non-recognized-fp3-device-in-fastboot-on-a-win10-device-easy-e-os-installer/68674/15. Since I had previously connected my tablet before, with it disconnected I went to device manager>view>show hidden devices and there was something like other devices. I went to update driver>update driver from windows update and there it took me to Windows updates in settings and I saw optional drivers and installed both of those (something like android and fastboot). I also read this (https://forum.fairphone.com/t/problem-to-unlock-device-state-with-fastboot-command/69113/2) then installed the https://developer.android.com/studio/releases/platform-tools and added the path to the environment variables. I opened the tablet in fastboot by pressing volume up and power while closed, then in recovery chose boot into bootloader. I plugged the tablet to PC, ran cmd as admin, ran adb devices that started but listed no devices. Then I ran fastboot devices and it listed my tablet. I opened ubports-installer (not as admin), chose device manually and followed instructions and files pushed to the device in recovery mode. It then rebooted into ubuntu logo, then was turning and eventually I had Ubuntu Touch up and running.

Forgive me, I'm a newbie posting on this forum. Sorry for the length...

I have this tablet and it's been gathering dust for years. These are the things I have tried (specifics might be hazy as I tried lots of things from different forum searches):

1. On tablet went to settings and toggled developer mode on. On my Lenovo T530 laptop running Windows 10 64 bit pro, ran ubports-installer as administrator and it detected my tablet. I picked install Ubuntu touch, picked erase data and fast boot. Tablet boots into fastboot mode and Installer shows Flashing Firmware... but it's stuck there and never changes. I tried installing the universal adb driver and same result. Tried different cables, different ports, making sure the ports are 2.0. Always detected by Windows, it's MTP mode but no go. There was the Windows defender blocking thing and I disabled that in settings. I tried previous versions of ubports-installer to no avail. I tried choosing stable and devel versions of ubuntu touch.
2. I tried resetting the tablet settings and re-enabling developer mode.
3. Tried SP_Flash_Tool_v5.1924_Win and it also was stuck at fastboot.
4. I tried this on another Windows 10 Pro PC (Lenovo S20 4157) with the same result and same working cables. I'm not sure if I tried not running ubports as administrator. I tried swapping the hard drive and installing ubuntu but that was a no go. I tried running commands in live version but didn't work either.
5. I made a VM on the laptop and installed Ubuntu 20.04 LTS with guest additions/extension pack. I updated, plugged in tablet, it is detected in the VM. I installed ubport-installer through the deb and ran it sudo and same it was stuck at flashing firmware. I tried following tutorials to fix udev permissions, removed and reinstalled adb, fastboot and ubports-installer. adb devices would detect the tablet, but fastboot devices would not and fastboot oem unlock would show waiting for any device before and after adb, fastboot and ubports reinstall. It's like once in fastboot the tablet is not detected.
6. In the VM I ran ubports-installer without sudo, I noticed it wanted to set the udev rules so I let it (It might have done that before but I don't remember) and it still was stuck at flashing firmware. I tried again and chose without fast boot. It showed adb waiting and I booted from fastboot to regular mode on the tablet, then the screen was pushing the firmware. Bar progressed and I walked away, when I came back tablet was in recovery mode and at the bottom ubuntu update. Installer showed the pass fail wonky popup and in the back i could see success. I restarted tablet and it was stuck at Ubuntu logo screen. I can get into recovery mode and I tried resetting but still stuck at Ubuntu Logo.

So I'm no professional but I'd say the issue is due to tablet not being detected by fastboot? I don't know how to make tablet writeable by the PC? I also have a 3rd PC an M93 Tiny with Windows 10 I can try. I can also put ubuntu on it but it's a pain swapping the HDD (I don't like having two HDDs 'cause I find dual booting always screws up Windows in my experience). I just want an updated OS for the tablet - I would accept Android even but that's a lot of research too! Thank you!