mbp-ubuntu | UBUNTU 20.04 for Mac with T2

Reduce the size of the mac partition in MacOS. Turn off secure boot and allow booting from external media - https://support.apple.com/en-us/HT208330. Download .iso from releases section - https://github.com/marcosfad/mbp-ubuntu/releases/latest. If it's split into multiple zip parts, i.e.: livecd.zip and livecd.z01 you need to download all zip parts and then. Next you can check the SHA256 checksum of extracted .ISO to verify if your extraction process went well. MacOS: shasum -a 256 ubuntu-20.04.iso Linux sha256sum ubuntu-20.04.iso please compare it with a value in sha256 file available in github releases.
Reduce the size of the mac partition in MacOS HowTo: Steps to Resize Mac Partition
Turn off secure boot and allow booting from external media - https://support.apple.com/en-us/HT208330
Download .iso from releases section - https://github.com/marcosfad/mbp-ubuntu/releases/latest If it's split into multiple zip parts, i.e.: livecd.zip and livecd.z01 you need to download all zip parts and then join split files into one and then extract it via unzip https://unix.stackexchange.com/questions/40480/how-to-unzip-a-multipart-spanned-zip-on-linux or extract downloaded zip parts directly using: on Windows winrar or other supported tool like 7zip on Linux you can use p7zip, dnf install p7zip and then to extract 7za x livecd.zip on MacOS you can use the unarchiver from AppStore: https://apps.apple.com/us/app/the-unarchiver/id425424353?mt=12 or you can install p7zip via brew brew install p7zip and use 7za x livecd.zip command mentioned above to install brew follow this tutorial: https://brew.sh/
Next you can check the SHA256 checksum of extracted .ISO to verify if your extraction process went well MacOS: shasum -a 256 ubuntu-20.04.iso Linux sha256sum ubuntu-20.04.iso please compare it with a value in sha256 file available in github releases
Burn the image on USB stick >=8GB via: dd Linux sudo dd bs=4M if=/home/user/Downloads/ubuntu-20.04.iso of=/dev/sdc conv=fdatasync status=progress MacOS diskutil list # found which number has the USB sudo diskutil umountDisk /dev/diskX sudo dd bs=4096 if=ubuntu-20.04-XXX.iso of=/dev/diskX if dd is not working for you for some reason you can try to install gdd via brew and use GNU dd command instead sudo gdd bs=4M if=ubuntu-20.04-XXX.iso of=/dev/diskX conv=fdatasync status=progress Rufus (GPT)- https://rufus.ie/, if prompted use DD mode Please don't use livecd-iso-to-disk as it's overwriting ISO default grub settings and Ubuntu will not boot correctly!
Boot in Recovery mode and allow booting unknown OS
Restart and immediately press the option key until the Logo come up
Select "EFI Boot" (the third option was the one that worked for me)
Launch Ubuntu Live
Use Ubiquity to install (just click on it)
[IMPORTANT] Select the options that work for you and use for the partition the following setup: Leave the efi boot as preselected by the installer. Your Mac will keep on working without problems. Add a ext4 partition and mounted as /boot (1024MB). Add a ext4 partition and monted as / (rest). Select the /boot partition as a target for GRUB installation, otherwise the system won't boot.
Run the installer (In my case it had some problem removing some packages at the end, but this is no real problem)
Shutdown and remove the USB Drive
Start again using the option key. Select the new efi boot.
Enjoy.