Floor plan of a single-family house without a basement, 3 children's rooms, and an office

You either have to like the window to the terrace from the bedroom or not. Privacy is better when the bedroom is on the upper floor.

Building envelope, building line and boundary: 3 meters from the boundary

What is that in red and blue in one of the drawings? Looks like building lines, at least building envelopes to me. Ridge direction specification? Yes, right?!
If the bedroom is on the ground floor, then not in the entrance area. Preferably top right according to the plan.
If north is actually at the top in the plan, I would pay attention to west-facing windows for the living room.
If possible, I wouldn’t pave over half the property with courtyard. There’s not much left for garden, terrace, etc. I would use more brainpower on terrace and garden access than what has been done so far.
The budget won’t fit.

First of all, thank you very much for your ideas and suggestions! We will especially have to think again about the open-plan area.
Regarding the garage... we have and only need one car and that is not going to change anytime soon. Therefore, we actually had the door to the utility room changed from the top of the plan so that there is room for a shelf here.
The garage is already planned to be as large as possible. The house will be about 8.5 m x 12.5 m in size. So we are already almost at the limit here. Unfortunately, it can’t be much bigger. Originally, a basement was planned, then things could be spread out a bit (office, pantry, utility room, technology in the basement), but this fell victim to the high interest rates :(
Do you have any concrete ideas for the open-plan area? It seems the pantry is mainly the problem here. Would a different kitchen layout open up the open-plan area a bit more?
We would like to have a large working surface and think, for example, that an island of 2.5 m would be too small for us. Unfortunately, we are not fans of wall cabinets either.

Do you have any concrete ideas for the open space? The pantry seems to be the main problem here. Would a different kitchen layout open up the open space a bit more?
We would like to have a large work surface and think that, for example, an island of 2.5m will be too small for us. Unfortunately, we are also not fans of wall cabinets.

Yes, see my above post: Plan anew and start with the upper floor, then work your way down. The open space will almost come about by itself if you plan the rest properly.

What is that in red and blue in one of the drawings? Looks like building lines, at least the building envelope. Ridge direction specified? Yes, right?! If the bedroom is on the ground floor, then not in the entrance area. Preferably top right on the plan. If north is actually at the top of the plan, I would pay attention to west-facing windows for the living room. If possible, I wouldn't cover half the plot with courtyard. There's not much left for garden, terrace, and so on. I would put more thought into the terrace and garden access than what has happened so far. The budget won't fit.

Exactly, that is the building envelope. Ridge direction is specified. Therefore, I wouldn't know how we could pave less if you also want to drive into the garage...

We also considered the bedroom top right on the plan, but then kitchen, dining room, and living room would be in a line. We currently have that and we don't like it.

Regarding the budget... we have already obtained 4 different turnkey offers, all under 500,000 euros.

How good are your skills in "reading construction and performance specifications"? Turnkey is undefined.