First Alert's new Onelink smoke and carbon monoxide detector is basically a Nest Protect that's specifically designed to work with Apple's HomeKit system, alerting you to emergencies at home, even if you're not there.
Two versions of the Onelink detector are available now: a battery-only version for $US109, and a $US119 plug-in version with a battery backup and a nightlight feature. On both models the battery is non-replaceable, but good for ten years which is when you should be replacing your smoke and CO detector anyways.
Like smoke and carbon monoxide detectors of yesteryear, the First Alert Onelink has an audible alarm alerting those in a home to an emergency as well as voice alerts, which explain what's been detected and where, if multiple units are installed in a large home.
The Onelink also connects to an iPhone, iPad, or iPod Touch over Bluetooth to sound additional alerts on those devices, and also allows you to silence false alarms remotely. In the event of a real emergency, the detector will actually switch to the home's wifi network so that connected iOS devices can be alerted even if a family is away. Otherwise, it sticks to Bluetooth to help conserve its own battery life so it can be on guard for the next emergency. Unfortunately there's no word on Australian availability.