Construction costs are currently skyrocketing

You apparently have to have a 65% share of renewable energy, but a gas heating ban itself was withdrawn again due to non-implementability.

I also see no necessity from the perspective of an old building owner to sell something below value.

Doesn't it ultimately come down to the same thing? So far, one could sneak in the renewable share with solar thermal energy, but at a 65% quota, that will hardly be possible anymore and won't be economical either, since 65% clearly requires integration into the heating circuit, instead of just heating domestic hot water as before. Hybrid gas/heat pump? At least in new buildings that's nonsense, maybe something for existing buildings so that you don't have to convert to low-temperature (surface) heating. Although pure heat pumps have already improved even at high temperatures.

So in new buildings, heat pumps are certainly always the best choice, but for old buildings, which mostly concern this, there are indeed a few alternatives to heat pumps. And here I would certainly consider pellet heating. You don't have to turn the whole house upside down for this (but you need space in the basement). A combination of a small heat pump with gas heating is also conceivable. Of course, you can't achieve 65% with solar thermal or photovoltaic, that's true. Unfortunately, there simply isn't a really good solution if you don't want or can't renovate extensively. I once thought pellets were a good idea. But when you hear that pellets are often dried with gas or that forests are being cut down in Eastern Europe specifically for this, it somehow takes the desire for this option away again. Not to mention the exorbitant costs that each of these solutions causes.