Use meshtastic and an ESP32 wired to the detector.
I like it and it certainly doable but it seems a little janky to me. I really wish there was a hacker friendly, non-cloud "connected" solution. I know we're in the minority with that sort of thing and most people want user friendly..
Again, thanks! I will start looking for smoke detectors that I can read the state with an esp32 or similar (maybe just put one of the detectors next to and already running raspberry pi?). I guess I was thinking of an out-the-box solution but maybe I'm dreaming (-: