Issue description

I had the displeasure of touching this code in #293542, and it is obvious that this tool has utterly bitrotted. I am not convinced it should be using the C++ API to begin with.

It really should be rewritten to use the CLI or C API. All the info is there and can absolutely be acquired via the CLI with a clever bit of Nix scripting.

Technical details

Please run nix-shell -p nix-info --run "nix-info -m" and paste the result.