It’s use case is to make it easy for a server admin to be able to reproduce a given server in an exact way.
You then take the config to a lab, upgrade and/or make a change. Then redeploy the new build in a very controlled manner effecting minimal downtime.
When used on a home desktop the config has the potential to become a chore in itself to administer which is more suited to those who prefer a minimal install.
If you like to tinker and try that latest fad app nixos is not going to be nice for you.
XFCE and/or AwesomeWM