Construction costs are currently skyrocketing

Photovoltaic prices are global, we can hardly influence that with our market

That may still apply to the selling price in China.
But local/regional marketing will capture every possible profit margin in sales in a very granular way.
Prices are then always as high as the (local) demand allows.

It does not matter at all whether the prices are reasonable, necessary, or appropriate.

I am also watching this with interest: it is already the case (in BaWü) that one hardly receives any offers. Or if they do, they are partly marked up with a 100% defense surcharge, or without an installation date (which is very important due to the payment). That means if this does not ease soon, the obligation unfortunately will not apply to a normal, functioning market, but to an extreme undersupply. And what that will do to prices should be clear...

I believe there would be a significant push if the access possibilities to a KfW loan were simplified.

I can agree with you for me and my husband. We did try, but then decided to build only the standard energy saving ordinance house because we couldn’t cope with all the regulations, laws, costs, and benefits. We just didn’t get it. Recently, I searched (for another forum user and myself) for the regulations and rules for greening a KfW carport roof, which in principle should be just a small thing. According to various providers and the consumer protection agency in one of the federal states, they are subsidized, also by municipalities, but despite about 2 days of research, I’m still no wiser. Well, it’s probably due to my lack of cognitive abilities.

We did try, but then decided to build only the standard Energy Saving Ordinance house because we couldn't cope with all the regulations, laws, costs, and discounts. We simply didn't get it.

Does your 'conscious decision' to heat with gas also fall into that category? You are building a timber frame house that can reach KfW40 EE with a snap of your fingers and then gets buried in subsidies, and you ignore these possibilities? There are professionals for the details, and they should also be able to explain that to a layperson. I don't mean to offend you, but these topics are more fundamental than casement windows.

Unfortunately, it is true that the German regulatory frenzy has managed to make these topics appear more complex than they are. There is still plenty of room for improvement.

...Although we tried, we ultimately decided to build only the standard energy-saving ordinance house because we couldn’t handle all the regulations, laws, costs, and subsidies.

In such cases, a compromise solution might be sensible:
During the roof construction, common mounting anchor points are installed directly.
They then protrude between the roof tiles but don’t really bother anyone.

But later, after clarifying finances and the market situation, the photovoltaic panels are purchased and installed.

This way, all options can be kept open with only marginal additional investments during the house construction phase.

In such cases, a compromise solution might be sensible:
during the roof construction, common mounting anchor points are installed directly.
They then protrude between the roof tiles, but don't really bother anyone.

But later, after clarifying finances and market conditions, the photovoltaic panels are only then purchased and installed.

This way, you can keep all options open with only marginal additional investments
during the house construction phase.

Unfortunately, you end up paying because the scaffolding has to be rebuilt. This way, you can use the construction company's scaffolding and save a few hundred euros.