OK, comedy time!
I’ve reinstalled completely fresh. Then I installed the Nvidia drivers:
What you’re about to see is breathtaking. (This is after driver installation and reboot - I did not touch anything…)
The screenshots are off to the side for some reason but the whole of the screen is full - not with the black around it as in you see here.
Yeah, I think I should. This is perplexing but also funny.