Cost estimate, bungalow 130 m2

Ridiculously expensive for such a tiny house without extras.

Note that at first glance, you only build a "tiny house" here. However, this is relativized by the fact that the attic can be developed.
But yes, as I also wrote, the price could certainly be reduced by a good €50,000, then it is better positioned.

It’s going to get pretty dark in there. Except at noon, then you get grilled. Plan external shading!

All living spaces have window areas of at least 1/7 of the room's floor area.

All living rooms have window areas of at least 1/7 of the room's floor area.

For a 20 sqm room, that is 2.8 sqm. That is not much more than the size of a larger room door.

1/8 is the prescribed minimum size

Finally, a down-to-earth counterproposal to the increasingly common bigger, more expensive, fancier here.

I basically agree with you on the size. However, here they are cheating in a very down-to-earth way: instead of placing space-consuming storage rooms, i.e. normal wardrobes, shelving dimensions are used. Desks are preschool size... A cold storage room that doesn't work, a front door with a RBM of 90 cm... is that even allowed? No paramedic can get in there... oh, what's the point of going into detail. Is this supposed to be a residential building at all? You can technically draw a 5-room house out of 95 sqm, but I don't see function or quality.