The encore controls “firefighter” is a really interesting device. I had thought about something similar before. It’s an acoustic alarm, kind of like a glass break detector, but it has to be really close to the alarm it’s monitoring. Within 6 inches. It’s looking for a specific acoustic signature, in this case the fire alarm, and then sending a wireless signal to a two gig panel or a Honeywell panel. I’m not sure of the exact network protocol being used. It might be a proprietary zig bee. And there’s a lot of additional security stuff built into it. If I had to guess, I would guess that it is not compatible with smartthings, but you could try it and see.
I also just wanted to call out the other detail in your post for those who are not familiar with the individual devices.
Nest protect is not currently compatible with smart things, although who knows what will be added in the future. However it is a networkable smoke detector which is available in either hardwired or battery operated models. From this you can get a notification message sent. So it’s one possibility to consider.
FIRST ALERT ONELINK
The other is the first alert one link, which is also available in either battery operated or hardwired models. In this case most the hardwired models are only intended to communicate with each other. So when one alarm goes off all the alarms in the house go off. However there is a set up option where you use mostly hardwired models, plus one battery operated model, and that gives you some additional Wi-Fi notification options.
Both the hardwired nest protect and the hardwired one link should meet code in jurisdictions that require hardwired detectors. Then if you want to add either The firefighter or the battery operated nest protect it should be fine in terms of a city inspector.
ALARM PANEL ADD ONS
Similarly, if you hardwire to an alarm panel, in many cases you can add a Z wave communication module to the alarm panel rather then to each individual detector.
SECURITY FEATURES MAY BLOCK A ST CONNECTION
Again, it’s unlikely that any of these options will work easily with smartthings at this time. Many security devices, including smoke detectors, use some kind of proprietary method to prevent outside systems from interfering with their operation.
DON’T TRY TO MIX AND MATCH IF YOU WANT A WHOLE HOUSE ALERT
I did also want to mention that most interconnected smoke detectors do not “play nice” with smoke detectors from other manufacturers. It’s just a fact. You will see this warning in the manufacture documentation. Please heed this. If you try to set up a whole house communication network, hard wired or wireless, where one smoke alarm is supposed to trigger another, it really is best if they are identified by the manufacturer as being inter-operable. Otherwise you may get both False Alarms, and fail to trigger events.
I believe this is in part what the “firefighter” device is intended to overcome. As long as the alarm is UL listed as a siren, the sound pattern should be detected by the firefighter device. But I haven’t seen any reviews, I don’t know how well it actually works in practice. But definitely an interesting idea!