This uses propane [1]. Many millions of people and I burn methane to cook and heat our house so propane is not that a big change but I don't expect that we'll be able to put its piping inside our houses except for a short length.
It doesn't "use up" propane - it's a closed system that uses the propane as a heat transfer fluid. The hot water generated by the system is what will get piped around your house.
Propane is the refrigerant (R290). That would be closed loop not consumed.
Millions of people have counter top ice makers in their home that use propane as a refrigerant. If you have a gas line that brings gas to your stove, having a heat pump circulate that same gas as a refrigerant isn't much of a stretch. Especially if its replacing a gas boiler.