Wasn’t getting rid of freon a “change” in refrigeration?
Thermo-electric devices have been around for ages. We use them here at work to cool down electronic sensors.............
https://en.wikipedia.org/wiki/Thermoelectric_materials
Whether the refrigerant is ammonia, butane (like many small devices now), freon or some of the new freon substitutes the operation hasn’t changed. You might change the pressures and temperatures it operates at but it still works by compressing a gas into a liquid and then allowing that liquid to expand back into a cold gas.