At first glance I might have installed all that was necessary for running the card. I will browse through the system in the next days to verify this, of course. Even Steam, Lutris and some games are behaving normal as far as I can say.
It is such a relief that thanks to your idea I didn’t had to reinstall - or to leave Endeavour at all!
Actually - those ‘extra’ items are what the arch-chroot script does for you… if you do them then arch-chroot is unneeded. Back in Ubuntu days I used to run a script equivalent to arch-chroot when I needed in…