CPython is the only viable Python interpreter, and the Python language specification is "whatever CPython does". In my humble opinion this disqualifies Python from consideration as a language.

That doesn't mean Python isn't useful! It is in fact a wildly successful tool that has spawned a large ecosystem of packages and a diverse group of users. But it unfortunately does not qualify as a true language, for it lacks the necessary ingredients: a formal specification of the language and more than one implementation of said specification.

I'm sorry, what are PEPs, again?

PEPs are specification fragments. But it's far from a complete python language specification.