I think both efforts have been important and have benefitted each other. Nix has always had purity/reproducibility as tenets, but indeed it was Debian that got serious about it on a bit-for-bit basis, with changes to the compilers, tools like diffoscope, etc. The broader awareness and feasibility of reproducible builds then made it possible for Nix to finally realise the original design goal of a content-addressed rather than input-addressed store, where you don't need to actually sign your binary cache, but rather just sign a mapping between input hashes and content hashes.
Of course, yes— that was what I was saying. But the theory with content-addressability is that unlike a conventional distro where the binaries must all be built and then archived and distributed centrally, Nix could do things like age-out the cache and only archive the hashes, and a third party could later offer a rebuild-on-demand service where the binaries that come out of it are known to be identical to those which were originally signed. A similar guarantee is super useful when it comes to things like debug symbols.
