[capi-sig] How can we make Python's C-API more friendly for non-C languages?

In my C API strategy draft, there wasn't much opposition to the goal of being “easily usable from non-C languages”. But it's clear that as CPython devs we don't have that much relevant experience with those languages.

I would like to ask developers of Python bindings, FFIs and alternate C-API implementations for thoughts, suggestions, and pain points to help guide the future of the C-API.

I'll collect thoughts in this Google document, though I'm happy to discuss anywhere else: https://docs.google.com/document/d/1fDfF7JanOEyQ9awhKE87-Ajp3H4k7qXL3cmyzPMo...

I've already asked:

• PyPy/cpyext: https://mail.python.org/archives/list/pypy-dev@python.org/thread/44IO4GHWBEV...
• PyO3 (Rust): https://github.com/PyO3/pyo3/discussions/2346
• nanobind (C++): https://github.com/wjakob/nanobind/discussions/31

If you know more, please let them (or me) know!