Single-family house with gable roof approx. 137 sqm, 1 full floor

But that’s not my drawing, @RomeoZwo must have edited it like that.
We don’t have a basement.

Yes, I overlaid the blue trajectories on the original sketch. But if the terrain is different, the idea is probably really not feasible for cost reasons.

How old is the neighbor? How about planning the space in the east for the carport as a boundary development, and maybe only building the carport in a few years when the neighbor is no longer there? None of these are satisfying solutions, but I do wish you light and sun in the house after all. It seems important to you since the dormer is supposed to "flood the house with light." I just unfortunately don’t believe it really does.
But in that case (dormer meant to bring light into the house) the straight staircase with a rather open stairwell is not the wrong approach. You then have the light in the hallways rather than in the living rooms.

Suggests placing the carport to the front and downwards. Provides light in the west

exactly what we want to discuss with the architect tomorrow

What about the ridge direction? Is it predetermined or could you also rotate the house with the gable facing the street? Can the office be on the upper floor? Is the single-story structure mandatory?

How old is the neighbor? How about allocating the space in the east for the carport as a boundary development, and maybe building the carport in a few years when the neighbor is no longer around?

The neighbor was born in 1959 and is thus still with us for a few more years. I think we will do it roughly as described in and try to set the carport lower – it shouldn't steal too much light then.

But in this case (the dormer is supposed to bring light into the house), the straight staircase with a rather open staircase hall is not the wrong approach. Then you have the light in the corridors and not in the living rooms.

Since we won't have a door from the corridor on the ground floor to the living rooms, the light from the corridor should also fall into the living rooms, right?! I also think that not nearly as little light flows in through the west and east windows as is sometimes suggested here. I estimate that the architect can assess that quite well.

What about the ridge direction? Is it predetermined or could you also turn the house with the gable facing the street? Can the office be on the upper floor?

it’s about fitting into the surroundings (§34). Could you maybe post a Google satellite image of the area for us? The street names can be hidden there.

What about the ridge direction? Is it specified or could you also rotate the house with the gable facing the street? Can the office be on the upper floor?

Sorry, wanted to answer your question still. This is again a matter of interpretation of §34. Unfortunately, there is no house with a gable facing the street on our street. I will have to ask the architect about that.