venv and PEP 582 seem to solve overlapping but slightly different problems. venv packages a python environment (interpreter and packages) without inherently tying it to a project (a project specific one might be embedded in a project directory, or a shared one might be used somewhere else, and you might even have multiple used for the same project, e.g., for different python versions or to validate against different versions of dependencies, etc.), while PEP 582 ties dependencies (possibly for multiple interpreter versions) to a project, but leaves supplying and identifying the right interpreter to use to some other system.