NixOS

I want to learn and experiment with fully configuring a single user NixOS installation that is declarative. I've found quite a bit on the NixOS system-land side, but when I go into Home Manager user-land I'm not seeing very much around configuring the Desktop. I usually use XFCE but in trying to work with it I kept running across posts about how it wasn't well supported. So I tried KDE but found the same.What is the best supported Desktop with Home Manager? Or do folks just do the basics with nix stuff, and end up pulling in the rest of the config info into the home directory (like from a repo) as a work-around? Basically use nix stuff to retrieve files and put them into the correct destinations.