I'd say it's fairly feature complete, but not super polished - as so many 1 person projects. I still find it very useful, author is also still active in the community and pretty responsive :)

I wish there were some automated tools where you could feed at the binary, or a directory of binaries, and it would just return all of the nix package names you should add include with nix-ld.

https://github.com/Lassulus/nix-autobahn and specifically its nix-autobahn-find-libs comes pretty close at least? Were you aware of that already and is there something missing?