It's not irrelevant, because if SPEC 0 says that a particular Python version is no longer supported, then libraries that follow it won't avoid language or stand

It's not irrelevant, because if SPEC 0 says that a particular Python version is no longer supported, then libraries that follow it won't avoid language or standard library features that that version doesn't have. And then those libraries won't work in the corresponding PyPy version. If there isn't a newer PyPy version to upgrade to, then they won't work in PyPy at all.