Note that's somewhat out of date:

> `bin/switch-to-configuration` is a Perl script from the beginning

Since NixOS 24.11 the default is `switch-to-configuration-ng`, in Rust. That is a 2.8 MB binary, compared to NixOS's 55 MB Perl distribution. Thus such Perl-less systems shrunk that dependency by 20x regarding activation switching.

And since NixOS 25.11, `nixos-rebuild-ng` in Python replaces its former Perl counterpart, see https://wiki.nixos.org/wiki/Nixos-rebuild

Less than they used to be: https://github.com/NixOS/nixpkgs/issues/267982 https://github.com/NixOS/nixpkgs/issues/428908

There is a project by a group of nix/nixos enthusiasts aiming to replace some of these core deps https://github.com/manic-systems/nixos-core. I havent tire-kicked it much, but it seems useful.