Earlier quoted context omitted.
Previous comment is getting long, but if you want to get rid of things like "googlecloud-sdk/platform/bundledpythonunix/bin" you can use: nix-locate --top-level --regex '^/bin/python3' Which will only show packages with "/bin/python3" in the root. Most of the time this is unnecessary, but since python gets vendored in a lot of packages, it comes up with this example.
I can't tell if you're joking, but I'm not sure how these results told you anything. I find nix-index and nix-locate entirely unusable.
$ nix-locate --top-level -1 --regex '^/bin/python3'
qtile.out
python3Minimal.out
python311.out
python38.out
python37.out
python3Full.out
python38Full.out
sourcehut.python.out
python39Full.out
python39.out
python37Full.out
ihaskell.out
Also things like "python3" and "gcc" and such are going to show way more hits than, for example, "firefox": $ nix-locate --top-level -1 --regex '^/bin/firefox'
firefox-esr-102-unwrapped.out
firefox_decrypt.out
firefox-unwrapped.out
firefox.out