It all sinply just works™! Don't worry about configuration :)
And how goes your gpu acceleration?
I didn't know they upgraded from the user having to accidentally find out that they need nixgl, which isn't even in nixpkgs, and then dig through open issues to find a solution that might enable them to automatically start programs with it.
As long as you're not using relatively obscure software, you'll be more than fine reading the docs/manual :)
Are alacritty and kitty obscure or have a manual entry? I couldn't get either of them running.
And as for the manual itself, it's so trash that the only instructions for declarative package management use nix-env and aren't actually declarative.
