Comment by steve_s
There is basic GraalPy support in Maturin[0] and PyO3[1], the problem is often that packages require older Maturin/PyO3 versions and/or they use CPython-isms, semi-public APIs, etc., but it is getting better, for example [2].
It is fair to say that large projects with a huge set of dependencies will likely face some compatibility issues, but we're working on ironing this out. There is GraalPy support in setup-python GitHub action. GraalPy is supported in the manylinux image [3]. Hopefully soon also in cibuildwheel [4].
[0] https://github.com/PyO3/maturin/pull/1645 (merged)
[1] https://github.com/PyO3/pyo3/pull/3247 (merged)
[2] https://github.com/pydantic/jiter/pull/135 (merged)
[3] https://github.com/pypa/manylinux/pull/1520 (merged)
Appreciate the further details, thanks! This is a huge undertaking, good luck, and I'll be checking back in here and there.