The Sonoff Magnetic Contact Door/Window sensor can be set as an alarm sensor on the RF Bridge. This alarm can be used to trigger a scene created in the eWelink app (this only started working recently).
Unfortunately, it doesn't currently work in IFTTT and so cannot be used to trigger any actions with other products (although it can trigger a button press for a remote that is paired with the RF Bridge).
I have got my RF Bridge to switch RF Light switches on and off. I can then control my RF Lights from Google Home. It works pretty well so far.
I had very difficult to pair the device with app and after at last added in app as Rf sensor and added the door contact only 4 their is no choice of adding any more maximum 4 device only
during Alarm door contact opens does't recognized which door is has open their is no option to choose door description it just common alarm notification pup-up on phone app
the sonoff wiki page - https://www.itead.cc/wiki/Sonoff_RF_Bridge_433 - lists code encodings the bridge supports - PT2260, PT2262, PT2264, EV1527. Is a sensor using one of those guaranteed to work? e.g. this one: https://www.aliexpress.com/item/SmartYIBA-Battery-Powered-433MHz-EV1527-Wireless-Smoke-Sensor-Detector-Alarm-for-Alarm-System/32856013726.html
I'd love to connect a number of smoke alarms to it, but don't want to buy a handful just to find one that works.