-
I think the problem is they're under quite strict regulations so not allowed to be linked through a potentially flakey wifi.
I have the Google ones as I live close to my work and figured I'd want an alert if my house was on fire rather than waiting to smell smoke. Not sure I'd recommend (disregarding the extortionate price) as we've had a few false alarms (I need to clean the kitchen one, had another replaced under warranty) which is pretty scary in the middle of the night. Advantage is it tells you where the 'fire' is so I knew where to look. Also a warning when it gets a bit smokey though I always just end up pulling out a chair and pressing the button anyway as it's faster than finding the app. Night light on the landing is handy for midnight loo visits too though I'm sure that could be done cheaper.
Polygon-
under quite strict regulations so not allowed to be linked through a potentially flakey wifi.
Yes - wirelessly linking them together on their own proprietary private network is how they should work, and the tech for doing so has existed forever, see any multi-device wireless burglar alarm from the 90s.
Howard
Wirelessly [non-wifi] linking them together should be a feature of the cheapest reg-meeting alarms. The tech to do so is ancient.