> I had been hoping someone would introduce the non-virtualenv package management solution that every single other language has where there's a dependency list and version requirements (including of the language itself) in a manifest file (go.mod, package.json, etc) and everything happens in the context of that directory alone without shell shenanigans.

If you are using uv, you don’t need to do shell shenanigans, you just use uv run. So I'm not sure how uv with pyproject.toml doesn't meet this description (yes, the venv is still there, it is used exactly as you describe.)