If you're going to insist that air source heat pumps don't exist then yes, heat pumps are very expensive. They do however, and especially in non-Scandinavian Europe, they will work fine.
Well then, I take it back that it isn't a shared definition in that sense.
But it's a pity, because the air source ones are basically AC units which can also run backward to heat your home, and if more people knew that, they'd install them.
Here let me prove it: https://www.carrier.com/residential/en/us/products/heat-pump...
If you're going to insist that air source heat pumps don't exist then yes, heat pumps are very expensive. They do however, and especially in non-Scandinavian Europe, they will work fine.