Read the docs for the first time and SO MUCH easier to do all the logic python side! Thanks @brooke . I have updated the clone link to include the pythonised way of doing it if anyone else want to use it or take it further. Indeterminate Switch - #3 by Neeeco
For my use case, the current state will do.
@stucork thanks for the anvil-extras pointer, might try that one as well.