The upgrade from 12 to 13 sounds pretty simple, using those steps.
The part that's still unclear to me is, is it an in-place upgrade that leaves all my apps intact, or does the system end up with a plain OS and I need to install all apps from scratch?
jjpprrrr's official documentation talks about "partition scheme has been switched", which sounds a little like data-loss. it also asks to "Format data/factory reset", and that would delete all apps, right? is that steps not required?