Nix is different, but I wouldn't say its _weird_. Nix the language is weird, but the packaging system is pretty straightforward. Imagine that every single thing you install is done in a chroot, so you need to declare exactly what it depends on to have it work. Thats it.

My point is that if you are comfortable with the effort needed for Arch, NixOS is _probably_ a better option because I think it does the same thing but better.