This is meant to collect the steps I took, which worked, and which I distilled from various documents and sites, and much reading of this forum, in hopes it might help clear someone else’s mind a bit… (and maybe mine, later.)

There were almost no obstacles…
adb & fastboot were run on Macbook Air in MacOS14 using platform-tools-latest-darwin.zip

Enabling Developer Mode
In Android Settings.. System.. About..:

• Quick taps on Build Number - OK
  In System.. {Developer Options}:
• Enabled OEM Unlocking - OK 1st try
  (After reboot, 2nd try, option was greyed-out OFF… message appeared: “connect to WiFi or contact operator” - once connected to WiFi, 3rd try - OK)
• Enabled USB debugging - OK
• I also changed default USB mode to “File Transfer”
  (probably superfluous)

The Hurdle
VolumeUp+Power did not boot device from OFF state to Fastboot Mode. Not my one, maybe others.

Unlocking Bootloader
On Macbook Air:

• I unzipped platform tools zip file in a Desktop folder ‘tools’
• Lenovo tablet ON and in Android
• Connected USB-C to USB-C
  In MacOS Terminal, as typed:
  cd ~/tools/
  ./adb devices - OK
  ./adb reboot bootloader - OK
  ./fastboot flashing unlock_critical - OK
  ./fastboot reboot - OK - booted to Android
  ./adb devices - OK

Installation with UBPorts Installer 0.11.2

• Lenovo device was recognised
• I selected 'Ubuntu Touch'
• Then 24.04… Stable
• Also 'Erase User Data'
  The installation jogged along until the tablet rebooted into Ubuntu Touch. I was not tempted to touch the tablet or the Mac. No.
  No, not a bit. Anyways, don’t.
• Ubuntu Touch booted its beautiful self!
• An App Update was available, so I accepted that.
• There was a request to allow the Mac to access an external storage (the tablet, must be) so I allowed that.
• Ubuntu Touch home screen and gesture prompts.
  Done.

I reported PASS for a successful result.
Now I’ll get started making it my own.

Regards,
KJU

[My first attempt with this device, after one former success with a Pixel 3a xl (bonito) and too much sad failure with a Nexus 7 (2013) (flo, or flox? with messed-up partitions…)]