Looks like they have no idea how to get their software working using Nix. The following blurb is absurd to most GUIX or Nix users:
NOTE: In most cases, end users should never compile fwupd from scratch; it's a complicated project with dozens of dependencies (and as many configuration options) and there's just too many things that can go wrong.
Users should just have fwupd installed and updated by their distro, managed and tested by the package maintainer. The distribution will have also done some testing with how fwupd interacts with other software on your system, for instance using GNOME Software.
I'm not sure I see the problem here? It does say most cases and I'd definitely consider Nix/GUIX users to be in the minority for this (on top of users who would even compile software themselves in the first place).
Also from what I experienced during my (not so long) time with NixOS, usually things in Nixpkgs were contributed there by community members who ported applications over to be compatible with Nix. Sure, it's a nice extra thing when the application developer does so out the gate, but given how special Nix and GUIX's environment is, the onus has never really been on the app dev.
I’m not pointing to a problem per se. I’m just saying that this dev dismissed the act of building this from scratch as impossible when it is not actually impossible. Honestly, I’m just trying to spread the word about Nix and GUIX because they make things that were previously considered impossible (like this) possible.
I see, that's plenty fair enough, although I don't think they meant it quite so literally (but rather as a method of lightening their support requests - I don't have any fwupd capable hardware AFAIK however I get the feeling fwupd is pretty popular).
I find it really cool what Nix/Guix are doing and I give major props to their communities for what they've pulled off, for what its worth.