For live debugging/fixing we were sharing a dedicated GitHub repo, and the candidate would share his screen while doing it. It was kinda of a mess, so I switched to a more static approach of sharing a MR and have the candidate explain what it does, and potentially comment on it.

TBH I wouldn't do that face to face, it's so unnatural I'd prefer white boarding or straight handing them a computer.

That's also where using an online coding platform where the candidate can run the code works a lot better, less preparation on either side, less surprises.