In the summer the warm exhaust from the fridge gets dumped into the kitchen along with heat from cooking. Then the cooling system has to work harder, or if there is no cooling system it just means less comfort and fans running more.
So I have to ask, why don’t refrigerators have a duct so the warm air can be vented outside in the summer?
In the winter I actually adjust the fridge temp to be colder so food lasts longer because the output is beneficial anyway.
How would you implement such a system without making it so complex that utility and versatility aren’t severely compromised? The efficiency gains would have to be pretty substantial to overcome the efficiency lost to making the refrigerators heat pump system more complex. It’s not like there is some kind of exhaust port on the back of a fridge that you can pipe outside. Have you ever looked at the back of a fridge?
Technology Connections on YouTube has several videos that explain heat pumps of various kinds: a refrigerator, Home heat pumps playlist.