Is a turnkey wooden house possible under €300,000?

I don't know about the others, but the floor plan and the photos are totally misleading.

- No measurements
- no utility room/technical room
- and photo 5 shows downstairs what you see, the open space alone feels like 60-70 sqm

I see a guest room on the ground floor and a bedroom upstairs. Where is the third bedroom?

and I wouldn't call the living area large either; from my point of view, it was skillfully photographed, and yet you can tell that it is not very big (see, for example, the size of the dining table)

As mentioned, the third room can be realized on the gallery. Thus, upstairs there would be two small children's rooms, downstairs a bedroom for my wife and me, and a living room that would more than meet our requirements.
Admittedly, it is not particularly large; it is only meant to illustrate that building a house that can accommodate my wishes on 105 square meters is absolutely possible. And what is possible on 105 square meters should also be possible on 130 square meters... of course, at a different price.

One should also consider that your example house is built on a basement. That is where the second staircase leads (and how stupid are actually different staircases). There is probably also technical equipment and storage space. So it is de facto significantly larger. If you now only look at the ground floor and upper floor and still want to find space for a utility room and storage, it will probably become clear why all of that does not fit into 100 sqm.

Draw the correct furniture to scale in every floor plan you like.

The house has a basement. The building services, laundry, and storage room are missing.

For example, the dressing room does not work. Far too narrow.

This house is just an example. What matters to me is to find out if there is any way to realize my ideas of a wooden house under 300,000 €. If Sonnleitner, a company that I would rather classify in the upper price range, can realize a 105 sqm house with a fireplace and gallery for 278,000 € (at that price, one can probably assume turnkey), then maybe somewhere out there there is a company that can build me a house like that, a size bigger, for that price or a bit more. I’m realizing it myself right now... Given these pictures, I just can’t give up the desire for a gallery yet...

Don't forget the additional construction costs, they are still missing