Floor plan planning single-family house / bungalow - 155 sqm

Show the size and access/approach to the property in the cadastral plan, it is not clearly visible in the aerial photo. You seem to plan the rooms and their effects in the floor plan, I would say, "differently" than the images of the visual examples suggest. Try planning more conceptually than concretely, then wanting and succeeding will probably align better. Due to the apparent lack of a corridor, the kitchen is practically in the middle of the actual hallway. Show the floor plans of the discarded evolutionary stages.

The floor plan is really not very practical, although you have already invested so much time in it. For example: when child 1 wants to go to the children's room after school, they have to navigate quite a slalom. And the narrow, poorly lit hallways feel more claustrophobic than spacious. Also, the fact that everyone has to go through the kitchen to get to bed or to the rooms to play I find unsuccessful. The kitchen is also difficult to furnish sensibly for the planned five people, as there is a significant lack of work and storage space. The pantry on the other side is also not very practical; you run yourself ragged if you store the supplies you need for cooking there. You can also clearly tell from the planning that you do not yet live with children. Do as Kati suggested. Take your wish list and go to a general contractor or an architect. Attached is a floor plan for a bungalow with four bedrooms - but that is 200 sqm.

I find a bungalow on a slope simply stupid - there are so many other possibilities to make use of the conditions of the property, save money, and find a stylish solution. But a bungalow on a sloping plot and the associated costs for the earthworks with that budget... you really don't need to talk any further about the weaknesses of the design. This is purely a pipe dream. Sorry for the brutality - but even if you still manage a sensible design for a bungalow. With your budget, it just won't work. And Kati's objection ([STAURAUM!!!]) is not just a side note for a family of five!

There is a lack of storage space.
Just the weekly groceries for 5 people, especially when the children are older, are huge.
In addition, clothes, toys, strollers, balance bikes, and so on do not go away; they are stored for the next ones.
Pans, cooking pots, etc., everything gets bigger.
Where should the mountains of laundry be processed?
It doesn’t have to be a huge villa, but the floor plan must be practical.
Quiet in the office, which is accessed through the living room. Only in the mornings when everyone is at school or daycare. Otherwise, 3 to x (friends, neighborhood children, etc.) kids are running around. Kids are simply loud and present.
The floor plan has too many corners, too little storage space, too few retreat options.

Barrier-free is a flexible term; thus, the floor plan is no less barrier-free than a two-story building.

I just think a bungalow is simply stupid on that slope

I wouldn’t have put it quite so harshly, but with

for about a year now we have been planning our own home and have already gone through many rounds (from basement to two-story, etc.).

I was quite surprised how one ends up with a bungalow. At twenty-nine, you might think that at thirty you basically start "getting old," or maybe one is shocked by the answer to the question about stair prices, but still, a bungalow here is at best Columbus’s scrambled eggs ;-)

Attached is a floor plan for a bungalow with four bedrooms - but that is 200 sqm.

Cool, it reminds me of a book I got as a teenager - full of American houses and floor plans :)
Do you have one like that too?

or maybe people are shocked by the answer to the question about stair prices,

It's like with a lifting station that you save on, only to realize later that a basement is bad if it's at ground floor level, because the garden landscaping becomes much more expensive ;)