In the context of Omarchy, the salient desire is to avoid affiliation with fascists. Which NixOS hasn’t exactly excelled at: https://en.wikipedia.org/wiki/NixOS#Community_controversy

(I say this as someone whose main laptop, desktop, and homelab are all NixOS.)

Since Nix have had some controversy (tldr), I'm just adding the Gnu Guix distro, as an (FOSS) alternative to Nix.

Both are 'declarative' systems that are build/configured from a configuration file - amongst other goodness.

Go Guix or go home

But what I want is to distromog on nixcels!