I recently tried Pop!OS liveUSB without a mouse connected to PC, there were some accessibility issues but one was unrelated to mouse and pretty cursed:
I chose system language to be something non-latin-based, and ended up with a keyboard layout that can't input English text. There was no way to change the layout and adding the US layout didn't work, because system showed that the US layout is already the one and only available. So I couldn't input commands to set things up but also couldn't click in the UI to set things up