Floor plan opinions single-family house 140 sqm 2 full floors

That's what the development plan says. Tell us what it's called. No link is forbidden here.

Where? I don't see that in your plan. Show the plan from the cadaster. You can also see what's going on in the surroundings there.

The development plan says nothing about it. The roof can be perpendicular or parallel to the street. Also all roof types. So I can rotate the house however I want, but whether it can be positioned offset to the side is unclear to me.

However, I have now tried to put your suggestions into a different floor plan again.

No, you have drawn exactly the same situation, only the entrance and technology have been swapped. The other things, including the poorly usable kitchen, you have copied 1:1. We are not talking about a 20cm shift or gain. That does not require a new design; it is about the kitchen space planning.

The question I ask myself is, does the floor plan work like this?

In my opinion, it has gotten worse by trying to improve it. You have worked out the insight that the staircase does not work differently. That is something already.

Attached is the upper floor.

Here is a tip: The stairwell at the beginning can probably be built over. Nevertheless, switching bedroom/bathroom is advisable. But even so, you can already see that the upper floor compared to the initial version is the winner here! I would therefore take the upper floor as the basis for the single-family house: transfer load-bearing walls, make the storage room, which you lovingly call pantry, more easily accessible (relocate), and start the all-purpose room earlier, thereby gaining space.

The idea is a car width of 3.5 and then 2.5 width to get out of the door and walk through or move around.

I am surprised that you are this generous with the necessary dimensions in the outdoor area, almost overly so. A parking space needs approximately 2.50 plus maneuvering space (I am reminded of garages, which are uncomfortable but still manage with 2.70 inside).
And inside you add 20cm. Fitting furniture tight against the wall is not possible anyway. With plaster on the wall, you should plan about 15cm less than the dimension given.

Without seeing the upper floor, I can't assess that.

I have only drawn the ground floor so far. The question I am asking myself is, does the floor plan work like this?

Starting with the upper floor answers the question by itself. Isn't the start of the already somewhat steep staircase a bit overbuilt here? I definitely like the fact that you draw it yourself, especially by hand, and to think of the interior walls as load-bearing in case of doubt / as a rule. And I repeat my "question" as to why you don't expand the floor plan following the building envelope (diagonal or stepped).

What else I notice:

I also looked in other posts and immediately installed a spiral staircase to keep the ascent away from the dirty area.

It didn’t bother you before that everything goes through the dirty area (this concerns not only the stair landing but also the WC). You can keep such points in mind, but not everything is possible, even on 140sqm, which is not a criticism of the size here, just a reminder that you simply cannot implement everything that is possible in a house over 160sqm.

Question", why you don't expand the floor plan following the building envelope (slanted or stepped).

I don't know what you mean by that. Therefore, I probably couldn't answer it.