My 2 cent would be to make the necessary changes in the standard library such that an external library (on pypi) can enable the feature. That lets us start wor

My 2 cent would be to make the necessary changes in the standard library such that an external library (on pypi) can enable the feature. That lets us start working with them, but puts no pressure on c extension developers to support it because subintepreters “aren’t standandard” but just yet another pypi library which might fail in combination with others. Then in a couple of years if the ecosystem adopt and supports them, it can be moved to standard.