Floor plan, two full floors without basement, 170-180 sqm

Also the question of whether direct access from the garage without an airlock is a good idea. The food regularly smells like rubber tires there or, worse, like exhaust fumes if they are still combustion engines.

And in the car, it smells like Bolognese. ;)

I like the floor plan! But I would also do without the pantry or airlock. Put tall cabinets in there for storage, make the office and thus also the wardrobe bigger. The open space is nonsense... I would NEVER give up spaciousness in the living/dining area just to save 7-8m². For me, there is nothing worse than a cramped open-plan room where I can (exaggerating) put my feet on the dining table from the couch. The current one is really very nice and you also have to keep in mind that you want to decorate it, especially with plants, dressers, etc. There should also be a certain spatial separation of the areas. You don’t want to have to turn the TV volume down to 30 every time the dishwasher is on.

The pantry will have a fire protection door to the garage that is airtight. So exhaust fumes with Bolognese shouldn't torture the nose. Nevertheless, it is more hallway than pantry.

the green areas are comfortable, much better than too tight. If the children should come, it is their play area. I have now learned, at someone's place the garden slide is in the WZ, and at another the indoor climbing frame. You need space for that too ;)

Die Aufschüttung wird nicht ohne.

Have you already calculated whether a volume-neutral "reallocation" might be economical?

So, to basement one construction phase (possibly garage & utility rooms?) - and use the excavation from that to backfill for the second construction phase (e.g., the main house?)?

Yes, Corona has demanded creativity. We have a trampoline in the office and last year an ice rink on the terrace.
I would not remove the green areas. Whether it's the play kitchen, doll corner, yoga mat, or houseplant, it is simply spacious.

Actually, I wouldn't change that much.
The dining area, the location of the utility room on the upper floor, the gallery.
I think the children's rooms are appropriately sized for the house size.
I think it's important to reconsider the orientation. Sunlight or natural light is important.