Earlier quoted context omitted.
How does Nix work with less sophisticated package managers that run on top of it, e.g. Python's "pip"?
If you just use pip & co, nix will be unaware of it and won't care one way or another. It will basically treat your pip-installed stuff like it'd treat your sourcefiles or pdfs. Alternatively you can create derivations instead in which case the resulting artefacts will be fully understood and manageable by nix (I think there are integrations to do that e.g. tools like carnix which can automatically create derivations…
Also if you run pip as root (to install for all users at once)?