Earlier quoted context omitted.
What’s the difference between a reproducible binary and one they’ve built themselves? Can’t they just build it from source and check that the digests match?
I mean heck, since it's a Nix Package, couldn't they just build it with Nix as the build system? And if for any reason that is the issue (installing Nix on a foreign distros can be pretty invasive, containerized?), the recipe for how to build it is right there.
Is this some kind of joke?
Installing nix on a non-nixOS computer doesn't even require root. You can even bootstrap the entirety of nixpkgs that way. That's one of the most awesome things about nix and nixpkgs.