Compatibility for games will be the same under Nix as they are Debian, Ubuntu or Arch. If your using steam just toggle compatibility and you'll be set for most titles under that launcher. I've ditched windows in favour of Linux, jumped between Debian, Manjaro and settled with nix.
Nix has been around for 20+ years now, it's quite mature at this stage, but has lots of features under development.
For me, nix is a reproducible environment, the same code for my install will build the same working system with the same configuration for applications even if a drive goes bad.
My sensitive data is stored elsewhere, but my keybinds, themes and wallpapers, colour schemes for applications and even settings in those applications will be the same on a fresh install (so long as I've defined them π )
Majority of my config is identical between different machines, lots of reused config with minimal machine specific config.
My nexus one had an OLED display iirc, thing had huge volumes of burnin after 12 months.
I've not seen burnin on any of my subsequent devices, my S10+ is still going strong since 2019. Shame about the Samsung soc.