Floor plan single-family house approx. 160 sqm - suggestions for improvement?

Can you maybe say something about this?

No risk, no fun.

Is that possible?

Possible, yes, but illegal. I don’t know what is being checked. If construction is carried out in NRW under authorization exemption, generally nothing is checked, in the simplified procedure only spot checks. And with you, the stork will probably bring the planned children 2 and 3 only after the building acceptance as well. Nevertheless, there remains a residual risk that I am unable to assess.

Nobody is coming to "check". The only ones who actually come by and look are the bank.

Good to know
I understand that the bank checks. It is their security, and it would be foolish if there is only a garden shed on the property, but we go to the Maldives 5 times a year...
however, the bank has also said that they will now not measure or check whether the window is actually in the planned location, but that the house achieves the value as originally assessed by the bank.

Security and it would be silly if there is only a garden house on the property, but we travel to the Maldives 5 times a year...

The bank secures itself differently regarding what happens with the money. For that, there are construction progress plans.

I would not do it for the following reasons: if anything happens in the room, e.g., a fire caused by playing children (just as an example, this happens now and then), the building insurance or expert, police, and fire department will check. Result: The insurance will not pay.
For me, that would not be a solution.

So with the building insurances I know, documents from the building application never had to be submitted. Maybe you have different experiences? To be honest, I have completely different worries than financial ones if there is a fire in the children's room. (Of course, one always assumes that this does not happen. But that is known to apply to all insurances )

Moreover, especially in the context of the low interest rate level, many old houses are being renovated and completely redone (in the interior). You don't need a building permit if the bathroom is swapped with the kitchen, the floor plan is changed by adding or removing walls, etc. At least in our circle of friends. A lot is also done independently after purchase, so I don't believe it is otherwise known if it requires approval. We will now probably actually create a storage room upstairs that will also serve as such. Until a room change takes place, several years will pass due to family planning, and then we will see what we do...

As for the building insurance policies I know, documents from the building application never had to be submitted. Maybe you have different experiences?

As investigators, we get the house plans for the file... the insurance then requests the file at some point...