I’ve really been enjoying NixOS, and beyond learning the capabilities of the configuration.nix file there is a lot of value in using Flakes and Home-Manager which are employed by most NixOS users. These are very succinct and well done video tutorials to get them setup and how you can use Home Manager to control your .config files even switching between configurations.
A good tutorial on how to setup your .dotfiles to be pushed to Github and backed up where you can clone them to a new installation.