Is there a way to find all Python PyPI packages that were installed with easy_install or pip? I mean, excluding everything that was/is installed with the distributions tools (in this case apt-get on Debian).
pip freeze
will output a list of installed packages and their versions. It also allows you to write those packages to a file that can later be used to set up a new environment.
https://pip.pypa.io/en/stable/reference/pip_freeze/#pip-freeze