Tangentially, I find wallpaper to be fascinating as it's one of the few aspects of desktop UX that is basically still 100% open to self-expression. For functional reasons, every other desktop UI surface has converged with only a few minor variations. But the static desktop OS background - perhaps because it has no inherent functional purpose and remains covered most of the time - remains as a canvas.
Eons ago, there was a (paid) 3rd-party program for MacOS Classic that would give you a slideshow desktop background. The images were of the Golden Gate bridge, and were a timelapse over the course of a day. The changes were (afair) synced to your local solar time, so 'sunset' in the desktop background would line up with your local sunset.
I'd have to search to find the name of the program, but I kind of wish I had it back.