There is already a similar project but it's based on IFTTT only (https://github.com/OpenSmartHub/OpenSmartHub/tree/master ), thus requiring internet connectivity and it can support only a few techs.
My idea is to create a smart hub for zigbee devices that could work also offline (so stats and actions could be always available) and use IFTTT Maker to add IFTTT functionalities to eliminate the need to develop a companion app (basically using IF app to for triggers and actions).
The IFTTT recipe will contain both trigger and actions as payload (unlike usual IFTTT paradigm) so that we can program the local HUB to store and apply it offline.
Ideally I imagine an arduino-based sensor collector with a zigbee interface and a RPi for the complex HUB operations and "server" applications.