When did you last see a kerosene-powered fridge? It's about 40 years since I last saw one. Hence my 'obsolete technology' label.

Reverse-cycle (heating) heat-pumps rely on fans to extract the heat away from the machine and send warm air into the room. If you have electricity for the fans, you might as well use that electricity to power the heat-pump too.

The fans are a tiny part of the energy used by a heat pump, most of the energy is for running the compressor. Electric heat pumps are more efficient and economical than electric heat, but still generally more expensive than gas heat, and impractical compared to gas if that electricity itself is made from gas in the first place.

If you power a heat pump with gas directly, you are effectively getting over 100% efficiency: you keep all of the heat generated from the gas, plus are 'pumping' heat from outside. It's going to be even more economical than regular gas heat, which is already more economical than anything else.