I think that you are painting a bit of an unreasonably bleak view of pyenv. I think that one can easily get value out of it without being a Python expert. I’m not sure how I can refute your “yes, but you’ll eventually run into trouble. You just haven’t clocked enough hours yet”. I can’t prove a negative. But I’ll say that I’ve been writing Python in my day job for a decade.

But, to add to the list of problems, these Python versions IIRC do not compile with optimisation turned on, so they’re by default quite a bit slower than they need to be.