> Oh come on, it's easy: (satire)

If you've checked out a repo or unpacked a tarball without documentation, sure.

If you got it from PyPI or the documentation indicates you can do so, then you just use your tooling of choice.

Also, the pip+venv approach works fine with pyproject.toml, which was designed for interoperability. Poetry is oriented towards your own development, not working with someone else's project.

Speaking of which, a project that has a pipfile, environment.yml, uv.lock etc. and doesn't have pyproject.toml is not being seriously distributed. If this is something internal to your team, then you should already know what to do anyway.