> For one you need a sophisticated reverse heat engine

This is a very obtuse way of saying “refrigerator”, which is a type of heat pump.. a technology over a hundred years old. The simplest refrigerators/heat pumps are pretty simple — https://en.m.wikipedia.org/wiki/Absorption_refrigerator

That's a subsystem with three major sections, a working fluid, and its own heat rejection requirements. A resistive heater contains two parts - a properly placed wire and a switch.

Still say “sophisticated reverse heat engine” is a needlessly verbose way of saying refrigerator or heat pump. Also how sophisticated is something that is mass produced for devices sold under $100 in every big box retailer.

A refrigerator for a kitchen has drastically different constraints. The outside temp will always be something between 15-30 °C, the inside temperature will usually stay relatively constant unless you dump hot stuff in there.

Cooling for active outdoor technology has extremely variable outside temperatures (basically anything from -20 to 60 °C, or more if you take direct sunshine into account) and a constant generation of heat to be taken away.

Still I can't really think about any mass produced consumer item that includes a heat pump and is not either part of building/car cooling/heeting or a refrigerator itself.

Like mobile base stations of course have AC units and some amateur astronomers use peltier cooled sensors, but I would hardly call these mass produced consumer items.