I haven't tried yet, but YoLink specifically markets their LoRaWAN sensors as working in fridges: https://shop.yosmart.com/collections/smart-fridge

For the readings, I only really care about catching compressor failure within hours, as opposed to say, days, so for a freezer that's normally set to -18, I figure I'll just do something like "alert if temperature remains above -14 for >2 hours." Of my 4 fridges/freezers, only one has auto-defrost, so I guess I'll have to take that into account there.