I watch my CI pipeline spend a minute or two creating the virtualenv and pip install into it several times a day, despite the fact that nothing has changed (no change to requirements.txt, etc), and I wish there was a well-supported way to package up a venv into some kind of artifact (keyed by Python version, host platform and package versions) so we only had to rebuild it if something changed. This sounds a bit like that, but also sounds like something more complicated than what I was looking for.