Quick update: I followed @Oliver2’s recommendation in the thread…
… and settled for the HmIP-SWSD.
My main rationales:
- Available in my region (Germany)
- Not cheap, but also not too expensive (€ 59), unlike Nest
- No need to be run via a cloud service (e.g. smart life)
- Group alarm
- No need to tinker around (like with some of Blakadder’s solutions). Not that I wouldn’t have enjoyed it, but doing so on a security-relevant device would’ve felt odd. Plus, from what I unerstood, those solutions would’ve relied on openHAB to perform a Group Alarm.
- Low maintenance (10 year battery): I saw some devices that operate with WiFi and thus have a higher energy consumption
- Can be hooked up to openHAB (I do operate a CCU2 already, so no need for an extra gateway)
- Extra goodie: Can be used as an alarm siren.