They said GUI everything AND “just works”. I was more so referring to the latter.

My point is that nothing “just works”. With immutables, your system is less likely to break after updates, but introduce other headaches.

For example, immutable distros usually primarily use flatpaks. But not all apps are available as flatpaks, may have issues running under flatpak (ie IDEs), or have permission issues that you need some know-how to workaround. There may be an offiical package from the developers, but most immutable distros will discourage using such a package if it was an rpm. Even then, if you wanted to use the rpm, Universal Blue is moving in the direction of removing layering (natively bootc, replacing Fedora base). And also the fact that if you do want to overlay, you need to use the terminal.