Due to changes in Apple's policy, Notion is not Homekit compliant.
Notion is a great fit for the connectivity and service that HomeKit offers, but in the end Apple is not supporting cloud-based solutions. In short, we did everything we could for HomeKit compliance - we tried implementing adjustments, adding more functionality to the bridge, optimizing architecture - all to no avail, unfortunately.
What does this mean? We are a Home Automation Accessory to iPhone which means that Apple has verified both the quality and stability of Notion. What we won’t be able to offer is checking the status of Notion via Siri and a few other features that HomeKit offers. With that said, we feel very confident Notion still adds a tremendous value without Homekit.