It would be nice to enable more complicated workflows for the rules engine. I’m sure there’s a lot planned, I can see where the UI is going and it looks good, but I think there will always be a need for running actual code.
How about some way to run python snippets in the rule engine? I’m not sure how to approach that as an add-on.
You could always run some external script which monitors devices/properties and acts on changes. There’s a well-documented REST (and WebSocket) API that you can use: https://iot.mozilla.org/wot/