The final result of the add-on: https://github.com/semagnum/separate_...
Light Painter, as another reference for the build and test-related scripts: https://extensions.blender.org/add-on...
0:00 Intro + Explaining the add-on
0:33 License + Operator setup
1:26 Override keyboard shortcut
2:32 Separate by selection
4:56 Separate by material + loose parts
6:27 Zipping your add-on
7:06 Testing set-up
8:54 Outro