Semi-detached house in Hamburg with general contractor on own land (two + full attic floor, no basement)

How is one supposed to imagine that?

Well, a relative standard. Fixed prices tiered for service phases 1-3 (always only together), service phase 4 (fully) and parts from later SPs. But then it depended on what the GCs would do. Of course, as soon as the GCs didn’t take on much here, it would of course have become significantly more expensive and he would have also billed according to HOAI.

When am I supposed to have written that?

Sorry, then I summarized that incorrectly.

that Germany could cast the super-general contractor with it.

That would be a new show idea! That was not meant that way by me either. What I wanted to get at: If two GCs submit bids for quite different houses (external dimensions, windows, equipment and so on), then they are hardly comparable. That was the result despite all efforts when we tried to obtain bids without specifying a prior plan. (Setting aside that many GCs were really very good at ignoring the development plan and what was discussed beforehand.)

Trockenbauwarzen produziert.

... what is meant by that?

I think the wishlist needs to be cut first or the budget increased. Also, such restrictions like 80sqm of floor space are usually a hindrance in planning for tightly calculated construction projects. It's better to give the architect complete freedom and mention that you also want a garden. Preferably more specific like a terrace and vegetable patch or just a terrace for one person, the other a football field, etc.

Sorry, then I summarized that incorrectly.

That may have been preceded by me having expressed myself ambiguously in part. Can you show me (by naming post numbers or similar) where you have read the misunderstandings?

What I was getting at: If two general contractors submit bids for quite different houses (external dimensions, windows, fittings, and so on), then they are hardly comparable.

There are independent building consultants (at least for "prefab" houses, I have already mentioned colleagues here several times) who can provide you with a preselection, so you don’t compare a Mazda with a Maserati across the board. Often it only takes one conversation (or a few thread dialogues) for a professional to recognize which providers correspond to the building family by type. This way, statistical outliers can be prevented in advance. That costs far, far less than paying an architect to create a drafting template for the GC. The more significant comparability disruptor than differing dimensions are those in the construction service descriptions, against which a concretely fixed building volume does not help at all.
How close to the goal are you?

... what is meant by that?

When builders are supposed to build according to building permit drawings, too many questions are still open or there is the risk that they will be resolved instead by the respective "method do-it-this-way." Without a slot in the wall, the downpipe is then laid in front and boxed in with drywall.

I think, first the red pencil must be applied to the wish list here

For the red pencil, the wish list would first have to be taken out of the fog.

Besides, such restrictions as 80 sqm floor area are usually hindering for tightly budgeted building projects during planning.

Yes and no. The 140/145 sqm II+D SD35-38 semi-detached house of the usual suspects is about 6m wide per half in 12.5m depth, so the "eighty" threshold is not even close to being broken here; and here it is even allowed to be more generous in terms of the number of floors (although the OP has not yet sketched a verifiable house profile).