When I come home, I can have food heated up for me already. It's called a slow cooker. I don't need a 5G radio in my slow cooker for that to work. And what a 5G radio can't do is get the meat balls out of my freezer and into that slow cooker. Similarly thermostats on timers are older than cell phones.

If you want an automatically adjusting fridge, that can and should be implemented without the cell radio too. Put a RFID chips in food packaging that requests a particular temperature; the fridge then sets itself to the lowest temperature requested. A fridge that instead broadcasts the contents of your fridge to some corporation that does not have your best interests at heart is an abomination, but I do not doubt that whichever corporation starts selling them will try to mask this by framing their spy devices as ecologically friendly to make it seem morally unassailable.