GoveeLife WiFi Refrigerator Thermometer with Alarm, Wireless Digital Freezer Temperature Gauge with App Control, LCD Display, 2 Years Free Data Export, for Fridge Hot Tub (Only Support 2.4G WiFi)

Govee makes a sensor with a probe that you can put in the freezer and it has a gateway that works over WiFi. I don't have one but I would imagine you could set up temperature alerts fairly easily on it. They are about $40 on amazon. https://a.co/d/0enQZb1G