Pyenv's a different animal. It's meant for installing multiple Python versions at once so that you're not stuck with whatever dog your base OS happens to ship.

Pipenv tried to be what uv is, but it never did seem to work right, and it had too many weird corner cases ("why is it suddenly taking 3 hours to install packages? why it is literally impossible to get it to upgrade one single dependency and not all the others?") to ever be a contender.