[lazka]

They don't use pinning in their examples: https://cython.readthedocs.io/en/latest/src/userguide/source... and https://cython.readthedocs.io/en/latest/src/userguide/source...

[physicsguy]

Pinning depends on the requirements you as the consumer have, and the specific package manager (pip, conda, poetry, etc.) so it's hard to give guidance that's helpful when you're a library maintainer. Generally when consuming any dependency you should pin though...