Download all the files you'll need today. It’s now possible to run Ubuntu Linux on an M1 Mac, thanks to an early build made available by Corellium. The operating system is booted from a USB stick, ...
Besides the bootloader, the only other obvious thing is changing /etc/fstab. Although a 'grep -r sda1 /etc/*' (or whatever the USB device name is) wouldn't be a bad idea.