Provide a stable ABI for PyPy (like CPython's abi3)
It would be great for PyPy to add support for a stable ABI similar to abi3 for CPython. Something where a library maintainer could upload a wheel built with say PyPy 3.6 (7.3.1) and that wheel would be guaranteed to work with future PyPy versions (3.7, 3.8, etc...).
Currently, as I understand it, library maintainers can release PyPy wheels but they are only compatible with a specific PyPy version.
For background, the cryptography project has started using rust in its build process which is fine for CPython users but forces all pypy users to install rust. This feature would make it more feasible for them to ship pypy wheels: