Single-family house of 200m² in 45° angled construction

What do I mean by that?
A walker needs space, turning area, etc. That is not provided here. At least one of you will use it when you go downstairs. Just google "nullbarriere".

There are still quite a few things missing. Basement, garage, earthworks, incidental building costs.
The 7 will be in front of that.
Make sure to check out the financing section here.

A complete offer is already available, of course without incidental building costs.

Cost estimate turnkey KFW 40plus ~ €525,000

Never ever - not with the roof and basement. Not even the bare construction without basement and earthworks.

Where is the access from? From the left side street? Is that the main street? Or from the right side? If from the right, I don't understand the following: You value low noise/quiet, but bend the house so that the terrace faces the street/driveway? I think you have just as good protection from the street if you simply place the house parallel to it. This probably makes the floor plan simpler and the house cheaper.

Noise protection towards the street then...but in the northwest towards the street a huge window front, instead in the south/southwest a tiny terrace door.

I see it like the others, with the headline I "hoped" for 90° because I like something like that, but this little kink doesn't really bring anything...but it creates, for example, the super awkward hallway upstairs...

Where is the access from? From the street on the left side of the plan? Is that the main road? Or from the right side of the plan? If from the right, I don’t understand the following: You value low noise/quiet, but angle the house so that the terrace faces the street/access? I think you have just as good protection from the street if you simply place the house parallel to it. This probably makes the floor plan simpler and the house cheaper.

As can be seen on the site plan, there are two streets. The left one is the main road. The right one is the access road; the front part is paved for a few meters and then gravelled. The terrace faces that direction because it is not a through road but only an access road for two other houses.

A complete offer is already available, of course without additional construction costs

Something is missing

https://www.hausbau-forum.de/threads/liste-der-anfallenden-Baunebenkosten-bauseits-teurer.9737/

https://www.hausbau-forum.de/threads/warum-ein-Hausbau-fast-immer-teurer-kommt-als-kalkuliert.16237/

As far as I know, an air heat pump with hot water storage

Think carefully about that. In the end, it’s basically a hairdryer. What the heat recovery ventilation (HRV) can’t achieve is supplemented with electric heating. Photovoltaics only help to a limited extent. The less sun there is, the more you have to heat.
If you don’t want underfloor heating, then look at the Tecalor 2.5 or Stiebel LWZ 604 Air. I don’t know if there are others with a system like that.