Bungalow floor plan 160-170 sqm with basement

If you lack imagination, you just don't plan. That's not a problem. There are professionals for that.

Stay a bit more flexible. You put chains on yourself that don't have to be there.
For example, the position of the staircase?
Why even have a staircase?
Why not open?
And reconsider the roof. You certainly have about 80sqm of living space up there with light without giving up your hip roof, bright and cheap. You will spend the money elsewhere anyway.

the large entrance area, as mentioned, we have from Haus Vita..

In your, I would say, very free adaptation, one can still "recognize" a Weiss Vita, but that's already a top-notch hardcore imagination test :-)

You are just fitting out a Bulli with the engine of a Porsche.

Oh, it could even have been from Artz or Oettinger.

What I don't understand about the whole bungalow idea: everything is supposed to be on one level, but the children are meant to be as separated as possible. Even if their rooms are zoned separately, they remain on the same floor. And that feels "closer" than knowing the loitering teenager upstairs (in your case down in the basement). For me personally, a bungalow never gives the same cozy living feeling as a multi-storey house. It quickly feels like commercial space: here is a windowless corridor, there is another room, too much space in the middle of a room. Here they sell bungalows a bit like sour beer. These are the houses that nobody wants, then end up being bought out of desperation and due to few alternatives. In the past, there were plenty of bungalows in poorly imitated Fermette style. In just 20 years, your bungalow will take over the baton from the Fermette.

In the past, there were plenty of bungalows in (poorly) imitated Fermette style. In just 20 years, your bungalow will take over the baton of the Fermette.

Is that a term that would be familiar to every Swiss person, but only unknown to me Prussians?

A fermette is a type of farmhouse: bungalow, flat, long, lots of wood. Unfortunately, the "lots of wood" trend carried over into the 80s and later. Thus, appealing farmhouses and half-timbered houses gradually turned into imitation wooden horror cabinets. Often still with wooden ceiling click laminate. And without half-timbering, because it’s too expensive. So, a fermette is a half-timbered house without half-timbering, without charm, and often in bungalow style but then way too big.

Here they sell the bungalows like sour beer.

Here they go like hot cakes.

Fermette is a kind of farmhouse: bungalow, flat, long, lots of wood. Unfortunately, the "lots of wood" carried over into the 80s and later. Thus, attractive farm and half-timbered houses slowly but surely turned into imitation wooden horror cabinets. Often still with wooden ceiling click laminate. And without half-timbering, because too expensive. So, a fermette is a half-timbered house without half-timbering, without charm and often in bungalow style but then way too big.

I don’t see any wooden horror cabinets, huts or anything like that in the photo. I see a stylish house, which I wouldn’t necessarily build myself, but still wouldn’t disparage.