Nox is a part of your global developer environment, like Poetry, pre-commit, pyenv, or pipx. All of these tools are in a sense environment managers. Installing Nox with Poetry creates a complex and confusing situation because Nox also needs to invoke Poetry, and may end up installing itself into the environments it manages. Also, when “poetry run nox” invokes “poetry install”, Poetry will be executed as an indirect child process of itself. All of this might conceivably work (I haven’t tried it) but it will definitely be hard to debug when things go wrong.