Hello

to install a deb package it needs to have its dependencies in the repositories definid in the /etc/apt/sources.list file or inside /etc/apt/sources.list.d/ directory, so Gdebi can't search dependencies from pip.

Ubuntu 20.04 has python3-portio package in the universe repository. Debian Buster also has python3-portio in its repositories. If you don't have pytho3-portio I guess that you are using a distribution older than Ubuntu 20.04 or Debian Buster. If you can't update your distribution you always can use the ExtremeCooling4Linux AppImage version that is packaged with all its dependencies.