I have done it... to an extent. I was able to integrate my 120V wired smoke alarm system to IRIS. This was accomplished using the BRK RM4 Smart Relay which cost about $15 from Amazon along with an old version Iris Door/Window contact sensor (about $20 at the local Lowe's). I got the idea to use the BRK RM4 relay from other forums. Wiring that to the existing 120V wired smoke alarm system was pretty straight forward. To get the contact change of state from the BRK RM4 relay into IRIS I took apart the door/window contact sensor, removed the magnetic reed relay and in its place soldered in two wires that were brought out of the contact sensor case. I connected the N.O. contact from the BRK RM4 to these wires. After pairing the modified door/window sensor, I renamed it "Smoke Alarm Status" and created a rule to send me an email when it senses the closed contact. Now, this doesn't set off the alarm at the Iris Keypad, but that doesn't matter to me as all the smoke alarms alert at the same time anyway. But, when I'm away from home, I'll get an email that the smoke alarms are going off. Then, I can check my cameras as needed.
Photos attached of a few of the mods.
The photo with the intense blue light is where I put a UV cured epoxy on the wires to add stress relief to the wiring. In the close up of the wires on the door/window sensor board, the removed reed relay is shown on the table to the left of the sensor. There is also a pic of the final electrical box mounted in my utility room.
I hope this idea helps someone else!