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If you want it to do something like "send me a text message" or "page me", then you'd need to add things like a Prometheus export to Grafana Cloud (free tier) and then use Grafana Alerting to notify yourself, or to trigger Grafana On-Call so that you actually get paged when the power in your outbuilding has been tripped.
I used to use Pushbullet for this which was pretty nice.
Home Assistant app can also do it but obviously you need a bit more setup if you want it to work away from home.
Home Assistant.
Move your Google Home Mini into the room with the freezer and put it on the same circuit, and set up an Automation that triggers on the state moving to "Unavailable".
The only potential hard bit is figuring out how you want it to notify you. Most of the built-in ways assume notifying some other device, i.e. play media, flash lights, etc.
If you want it to do something like "send me a text message" or "page me", then you'd need to add things like a Prometheus export to Grafana Cloud (free tier) and then use Grafana Alerting to notify yourself, or to trigger Grafana On-Call so that you actually get paged when the power in your outbuilding has been tripped.
I would probably go the overkill way as I like Grafana (and work for them)... but hey, you can achieve the basics with just Home Assistant.