Single-family house 175 sqm without basement, too big?

The basic model is the Solitäre 165, of which you can only find various designs (i.e., with extensions) on the homepage.

A pity, because this way I find little information about how the base model would actually look as a building form. All the images about it make me wonder whether one has to be a rogue to speculate about a relationship between Schwabenhaus and Bien-Zenker. Both are connected to Living Haus. Living Haus is, so to speak, a subsidiary.
In any case, you have "emancipated" your version very far from this base model – up to the now straight staircase. What seems to matter to me above all is that it looks functional this way. Whether I also want to believe that in terms of terrain integration, I am not quite sure yet. Your words don’t quite "cut it" for me; a site presentation with elevation points would be "preferable" for me.

The land planning is still quite a sticking point, I don't want to sugarcoat that... But the fact is, the plot stretches the slope over a pretty good length (a solid 32m). So we assume that we can build the carport, house, and terrace at the same height without any problems. We are not yet sure how to proceed below, where the slope continues to fall in the garden. The municipality itself is not quite sure yet, but is currently being attacked by many builders who somehow have to reasonably regulate the height differences.

Do you see the problem as being in the costs or generally in the feasibility? I am already afraid that we might make a pretty big financial mistake, but don’t know how else to deal with it...

I hope for my heart rhythm that you don't now fall for the ridiculous idea that anything would be easier with a straight single-flight staircase. Floor plans with less than 12 m in edge length you wouldn't even have to look for - single-flight straight stairs are - like a dogma of symmetry, but at least these two ghosts only add up faintly - an absolute space hog.

I am currently following your advice and reading the other topic, and then I come across this post from you Do you also find the staircase in my floor plan that bad?

Do you also find the staircase in my floor plan so bad?

No. The fact that it still "works" for you has to do with the fact that, as I already said, you are not trying to cram "thirteen wishes per twelve square meters" into your floor plan. Probably due to the interaction with the high knee wall, things work out exceptionally that otherwise would not fit. But this is also known from nature: contrary to theory, the bumblebee can indeed fly. So your staircase is, so to speak, also a whim of the rule.

Once again on the topic of slope: I have attached the cross-section of the property. What do you think? What are your thoughts on it?

That looks to me like about 1.85 meters of height difference in the area of the house. According to the now memorized 11th opinion, that is a clear indication of a basement. However, without the insertion of the specific house into the property, it cannot be determined what kind of terrain modeling this would mean at which point.