Floor plan design single-family house (city villa 140 sqm) on a slope with double garage

@ OP
clarify what experts say about whether you can build on the filled ground - then a catalog house would be possible after all
or whether the foundation slab area needs to be replaced or if everything has to be removed.
The floor plan depends on the slope. The less earthworks, the cheaper.
Don’t dismiss the basement right away. Living basements are fully functional living space.
If the development plan allows it
Basement living
Ground floor children + utility room + technology
Upper floor parents
Same sqm smaller footprint

After that or during that, find a company that can build a simple house with 4 straight walls and a gable roof.
Think about whether you really want to build. You don’t just give up golden faucets, but many little things that are must-haves today.
Maybe get in touch with Nordlys. He might be able to help you find where things can be cheaper - not worse.

Region or not: you have a hillside property. There are awesome possibilities, but they are usually not standard and therefore more expensive than average.

I never said that you are naive. The prices he mentioned are barely reached by anyone here, especially not turnkey and certainly not on a slope.

Do you want to build like in the link?

Does your development plan allow that?

Check what can be done with the pile of earth. I would be hesitant to build on it. Just as an example, our garage driveway is installed and compacted in layers with 0/32 mineral concrete up to 1.2 m. It will only be paved next year because in some places it can settle by up to 5 cm.

A city villa is a classic slab-on-grade house on flat land.
What exactly do you like about the house? Maybe that can be adopted.