[vgnet]

AFAIUI, what you're missing is that PyPy can (and often does) interface directly to C libraries, from RPython. So the prospect of re-implementing those specialized codebases isn't a real issue: only the CPython-API based wrappers would need re-implementing. I believe those are a small part of the total code you mention.

[cdavid]

But those packages do not just depend on C libraries. They also depend on the numpy C API. If emulating the C API of CPython is too much non-fun work, I would expect the same to be true for numpy C API.