I learned that using nix on arch for the home directory in addition to pacman and the aur is quite an unbeatable combo that I prefer to having everything managed by nix. The problem with nix and nixos I see for one is that it leaves some performance on the table for reproducibility and that many packages are or cannot be packaged for nix. Additionally arch already is quite reproducible albeit not as much as nixos. Writing your own meta package with a simple pkgbuild to manage the system base seemed like a good substitute for me.