I wonder if WiFi detectors will link together if the house doesn't have the 3 wire to link to the other detectors so if one goes off the other go off.
Also does WiFi detectors sync to an alarm panel pro?
Or does the WiFi detector just give you the battery and other info on your phone?
The First Alert One Link model is linked using proprietary 900 MHz RF to one another. The WiFi portion is only used to connect to the router so the home owner can receive notifications whether that be push notifications, sms, e-mail.
I believe the latest First Alert unit is also Apple Home Kit certified so it will connect to any *Home Kit* system or controller.
With respect to the alarm system normally smoke, co, heat, sensors are hardwired using a relay which in turn is connected to one of the I/O ports the alarm system and this pertains to 120 VAC smoke alarm systems.
If a person decides to go the low voltage 2/ 4 wire that offers even more capability because the central station, home owner will know exactly which smoke, co, heat tripped the system.
Lastly, as I indicated assuming you didn't do anything else the alert notification with respect to these WiFi systems the message goes to the end user. But like I said it makes no sense at all because there are too many variables that will impact a person in not receiving the message.
Bottom line have the smoke alarms hardwired to the alarm panel and add in any of the battery operated units to add extra layers and zone protection. In my home I do exactly that the main floor and basement are all hardwired per CEC code and they in turn are wired to the security alarm system which is monitored by the CS.
To ensure a measure of fail over I installed ten more One Link Smoke / Co talking units to the system. This ensures if there is ever a surge event they can't be damaged by lighting etc. Obviously they also extend the protection layer because they are installed in every room, floor, zone I wanted to monitor.
