[nh2]

Note that's somewhat out of date: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