I know this is technically not an answer to your question, but as a fellow T1 diabetic (for 20+ years) and dad to diabetic child (currently 2½ years old): Is this something that regularly happens to you? I don’t know where you live, but in over 20 years of being a T1 diabetic I never had a vial of regular insulin go bad. I don’t have to worry about the cost of insulin as my insurance would without any questions replace any medications gone bad for me, but I understand that this is a luxury not everyone shares.
There are products (but I have to assume you are aware of this) that can help you with the temperature safe transport of insulin for everyday use (basically insulated pouches with an integrated cooling pad). That may be something you can look into if this is something you need to worry about.
I totally understand your concerns. We just don’t have such cold winters here in Germany. And I also understand your point more (also after having read your other comments). If the insulin vial in question is a spare it will most likely not being noticed if it freezes until it is needed.
In theory you could use the Bluetooth sensors of the companion app which can be used to detect BLE beacons. But that would require a special Bluetooth device that activates once a threshold temperature has been detected. Maybe such things exist (I’m thinking of (food) supply chain monitoring), but I am not aware of any.