Arch has always been 'beginner friendly' according to Arch users, so why can't Nix? /s

But, yeah, Nix can be really nasty to troubleshoot because of the lack of information. The Nix documentation is still PITA, and the much of usual Linux guides (which are everywhere on the internet) won't apply to Nix systems. You have to learn a lot.

If what you want is a simple system with a web browser and some games, this should mostly work, but Fedora Silverblue would provide much more integrated and solid DE for that purpose. Being image-based release-based distro, it does offer pretty decent UX. Nix is rolling release, and everything is scattered just like Arch.