> There are also heat pump cycles that can be driven directly with heat. Refrigerators based on that are relatively common here in Canada in areas without reliable grid electricity. Usually a propane or natural gas flame.

Notably, the propane fridges used in RVs (which AFAIK usually use ammonia for the refrigerant) are extremely inefficient. They have the huge upside of requiring very little electrical power to operate, but would never be my choice if I wasn't tightly limited on electrical power.