Create an Apple Automation to notify power cuts when at home

Question

I have some electrical noise at home, and would like to use test equipment to verify its absence during power outages.

I’d like to be notified when my power at home goes out, but I cannot find an easy way to script this. I have iOS devices (iPhone, iPad, HomePod) and assorted HomeKit automation equipment (bulbs, sockets). I have plenty on ancillary kit (Pi, Windows PCs, components etc).

The standard automation triggers which might be useful are for WiFi networks, but only when you connect, not disconnect. Likewise, charger disconnect triggers seem to go off when charging finishes and the charge cycle stops - which is not necessarily a power outage.

I would ideally like to know, day or night, when my home power goes out (which is likely to also affect the nearby noise source). I only care about reviving this notification when at home, and do not mind the odd false positive.

Can anyone provide inspiration for an approach please?