Realistic price 100m² bungalow

The entire construction project should be completed with a total of €250,000-€300,000 so that a monthly installment of around €900-€1000 is achievable.

Without or with land?
How expensive is a plot of land with enough space for a bungalow where you are?

Are local, smaller construction companies possibly cheaper?

Yes, often.

But then probably an architect would be needed if there is no ready-made floor plan program.

No, bungalow companies have their own floor plans in their files.

€2000/sqm for the house
Plus incidental construction costs
Plus outdoor facilities/terrace/paving/garage
Plus painter/floor coverings in the turnkey delivery

For a fireplace, your living space will be too small (danger of overheating)
Or a small one in a house wall. But the costs are probably not covered in the stated amount.

I also consider 300k including the plot to be tight, what are the square meter prices in your desired area? As the simplest saving measure, I would omit the double garage, you can always add it later. You can also do a lot yourself with the outdoor area if the plot is level.

What does Ytong do - are those shell houses?

What does Ytong do - are those shell houses?

As far as I know, self-build houses.

As far as I know, self-built houses.

So-called illegal worker complete packages.