New single-family house in southern Germany

the long-held dream of self-realization.

There is also something in between, namely a properly planned house that fits my needs. These are different for every person. NOT planning it individually or taking care of it does not mean that it will be cheaper; it will rather become more expensive eventually. We had a similar discussion here a few weeks ago, and there it was also said roughly: I don't need anything special, just a house, and I'll do the rest...

I currently see few reasons to deviate from a standard floor plan with living/dining room in the south and kitchen in the corner

.... is THAT a standard floor plan? There are thousands of standard floor plans.

Even with completely free planning, we would end up relatively close to such a floor plan

That shows that you don’t really appreciate the work of an architect if his free planning ultimately only results in any random internet copy. You want to build relatively small, with a workshop, sauna, photovoltaics, and much more; every square meter that is poorly planned hurts. Without proper detailed planning, however it is done, there is a great risk that it will just be more expensive in the end without any increase in comfort; there are reasons why people plan their houses for a long time, and they surely are not just about the pursuit of the "self-realization" you mentioned.

There are dozens of standard floor plans in your size and number of rooms. That’s why I wrote how you create your room program. You draw that in. Besides, no doll furniture is deceptive then.

There is too much money at stake to end up storing the books under the attic because no bookshelf fits, while you practice dancing in the bedroom.

Ask 10 people here about their exact requirements and you will get 10 different room sizes.

I am now less worried about the financing issue. The budget is roughly set and a bank will be found that will finance it on reasonable terms. Now it is a matter of aligning the wishes with the budget. There should be no budget overruns before construction starts ;)

It is then only a question of whether a) your budget is roughly correct, and b) whether any bank is willing to give you, as an individual, a loan of ~400,000€, and if so, whether the terms are reasonable. ;)
If your income is >= 4500€, it will probably work.

more like 120....

Once again, arbitrariness has destroyed the 130.
Although 130 is still possible. However, your room program screams for at least 140 if there is a two-story building on the lot.

office for me on the ground floor

large kitchen-living area

You definitely need more space on the ground floor than on the upper floor...

rotate your staircase out of the dirty area"

This line of thought is not clear to me. No one decides YOUR staircase or floor plan. Rather, it will work better if you – always taking into account the building law possibilities – first put together what will strongly shape your daily life, namely your floor plan.

With the promotional house, almost nothing is possible and individual.

The problem right now is that the focus is on the higher-priced home builders. That only allows for promotional offers.

My feeling tells me that buzzwords like Kfw, smart home, electricity storage, etc. come far too early in your mind and could therefore mislead you.

I also think these buzzwords not only come too early but are given more priority than the house itself.
But I admit: I have not followed the garden house thread. Did I miss something?

You can only edit for 20 minutes

Is that new? I only have 10 minutes :(

I see a gable roof house on this plot, so a bit more living space downstairs than upstairs. The gable can be on either side, accordingly the carports (together, then you have more) to the east or south. Just move some templates around.
By the way, I also see a standard floor plan here, e.g. a half-landing staircase in the north, a living space in an L-shape over south and west, entrance on the east, gable on east and west.
Or house rotated 90 degrees with entrance on the knee wall side...
If the basement is omitted, then also some refinements including the buzzwords from above.

Is this new? I only have 10 minutes

well..... then you probably only have the free version while I regularly pay a subscription....... or I just mistyped again

well.....then you probably only have the free version while I regularly pay a fee.......or I just mistyped again

What do you mean by only? You still have to pay :p