A “project" is largely a way of storing the definition of the state of a environment in a config file (pyproject.toml). It does a bit more, but you can basically ignore that initially.

It takes a couple of seconds to setup, and then you just use uv add instead of (uv) pip install to add things to the environment, and the project file is kept in sync with the state of the environment. I'm not really understanding what it is for the workflow you describe that you expect a tool to do that uv isn’t providing?