Gentoo Linux has overlays. You can compile packages from third party overlays.
Gentoo overlays are better designed than debian/ubuntu PPA(personal package archive)s and AUR(arch user repository).
Gentoo Linux is simpler than nix and guix unless you need reproducibility. Gentoo Linux doesn't require you to learn nix langauge or guile scheme. You don't need reproducibility that comes with nix or guix on desktop computers. I just manage dot files in my git repository without any infrastructure-as-code tool. For servers, nix or guix can help.
qmr•1h ago
amano-kenji•1h ago
You don't need to customize it, but you can still get packages from third party overlays.
The customizability is available when you need it or want it.
Learning to use gentoo's basic functionality doesn't cost a lot of time, and I recommend utilizing only the basic functionality in most cases.
Just stick to the basics, and you will be fine.