NGL, Having my own nix build cache makes me a lot less afraid to make big changes.

Like overriding SDL3 system wide.

(That's a good 200 rebuilds on my system. Luckily, I have a distributed builds as well, so I have an 1800X, a 5800X3D and a 6700k chewing through it)
(who knew so many things depended on ffmpeg, and that ffmpeg depends on sdl3)
If you're curious WHY I am overriding SDL3 system wide - the version in nixpkgs isn't actually new enough to properly support the Steam Controller. But a slightly newer version absolutely does.
Fun Fact, the 5800X3D is watercooled.