According to PEP508, you need to specify version numbers in the ./docs/requirements.txt file. I need this information to create a Flatpak with req2flatpak or flatpak-pip-generator. Building VPN apps seems doable within Flatpak.
Edit: it may be a bug in req2flatpak, since this requirements.txt seems to work fine with a Flatpak build. They probably don't use that tool but something else. I'll check the docs and issues with req2flatpak a bit better.
According to [PEP508](https://peps.python.org/pep-0508/), you need to specify version numbers in the `./docs/requirements.txt` file. I need this information to create a Flatpak with [req2flatpak](https://pypi.org/project/req2flatpak/) or [flatpak-pip-generator](https://docs.flatpak.org/en/latest/python.html). Building [VPN apps](https://github.com/flathub/com.protonvpn.www/blob/master/com.protonvpn.www.yml) seems doable within Flatpak.
Edit: it may be a bug in req2flatpak, since [this requirements.txt](https://github.com/ProtonMail/proton-python-client/blob/master/requirements.txt) seems to work fine with a Flatpak build. They probably don't use that tool but something else. I'll check the docs and issues with req2flatpak a bit better.