There are many flake repos which will have the blobs of stuff that you want, LLMs can help, even the nix wiki is good for stuff like gnome or KDE.

Basically the different automated install paths have a few different DE's and language etc setup, but the rest you find yourself (programs, utils etc)

Home.nix is "home manager" configuration which is like it sounds, the configuration of home which is less drives and sound card and more programs and config.