A supporting note - my first thought was "well the author wants to work in CTF/pentesting situations where root access might not be available" but it tuns out that https://nixos.wiki/wiki/Nix_Installation_Guide#Installing_wi... is pretty well covered these days. At that point the only thing is that nix is complex enough that it might be easier to invent your own package manager than to master nix[0]. (I don't know enough about your other suggestions to comment.)

[0] Don't take this criticism too harshly; I'm writing this comment on a nixos laptop;)