Ask HN: WiFi smoke detector that doesn't require Internet access

I'm looking for a smoke detector and CO2 sensor that I can connect to a private isolated Wi-Fi network. I want to be able to get the alerts and send to myself, but I really dislike connecting things to the Internet.

I find it hard to discover things like this because connected almost always means connected to a cloud server somewhere, with an app that polls that server.

Apologies if this question has been answered before, I've tried searching on here and on the greater internet but the ad copy is not very clear.

Thanks in advance!