Nice! I've been following HPy for a while, and I'd like to eventually implement it in RustPython[0] (the blockers to doing so are mostly on our part, not theirs). I'm hopeful that this will vastly improve compatibility for native modules for interpreters other than CPython - numpy seems almost impossible to get working in RustPython without something like HPy.

[0]: https://github.com/RustPython/RustPython