Air-water heat pump, gas, solar thermal prefab house, advantages and disadvantages?

In the pink forum, a Panasonic air heat pump is very popular. Modulating, very affordable, and easy to install. It might make sense for you to install, for example, two of them to better cover your different needs. But you really have to dive deep into the topic for that. The solution certainly seems better to me than gas from the tank. Nevertheless, you should seek advice from a specialist, preferably independent. So not from your house builder.