I’m pretty sure that’s not how refrigerant (not coolant) works.

Extra insulation around the expansion valve and piping may be necessary. Or possibly heating around them. But the main limits are the size and speeds of the compressor and fan(s).

Home heat pumps are getting much better in colder climates. But I’m not sure of the efficiency in vehicle sized units. I’m really interested in them for a camper project I’d like to build though. But might have to wait for more of the cars that feature them to arrive in salvage yards.