For getting a idea of how your games run check out protondb.com you can add your steam library to easily check your library.

For epic, gog and Amazon prime gaming you got heroic (https://heroicgameslauncher.com/) it also uses proton to play windows games.

GPU drivers are fine. AMD just works for gaming and Nvidia (depending on distro you need to install the drivers, search how to install them and dont install them from the Nvidia website) works fine if you just have a simple setup. The Nvidia drivers are improving alot by the way.

Random mouse, keyboard and other stuff is a hot or miss. Most of the time basic stuff simply works, but maybe there are no drivers/programma to set rgb or macros. (P.s. Try open rgb for rgb stuff)

You can always try with a dual boot. If you not used to Linux and like gaming maybe something like pop os

I made some posters in krita for work. Worked okay. Just make sure you start with the good ratio in px for printing.

Everytime I hear something about Plex I become a bit happier with my choice for Emby as media server.

At the time of building my then server I could choice between them(jellyfin wasn’t a thing yet). Luckily I picked emby