Floor plan: Advantages and disadvantages based on a gable roof of 229m²

At an interest rate of 3.5%, we can manage the monthly payment on a loan of €700,000.
Fixed interest period of 10 years.
The down payment and some additional equity are available.

195m² x €3,000/m² = €585,000. Additional construction incidental costs and furnishings are extra.
Although, as a previously satisfied Town & Country customer, I am still convinced that you can still get a turnkey house for under €3,000/m² that offers living quality significantly above that of panel buildings.

The Flair Duo has 180m², can surely be easily redesigned for a family by omitting non-load-bearing walls, and costs from €464,000 in the Munich area.
Shutters (probably only mechanical), air-to-water heat pump, underfloor heating included.

PS:
What do you mean by "we can manage"? Is that a rate at which you feel comfortable and still have room to live reasonably, treat yourself occasionally, etc.?
Or is that already the pain threshold where you can no longer afford a vacation on the North Sea?

When doodling with a ballpoint pen, you should stick with it at least until you can do it. I still start almost every project today with forty years of construction planning experience in this way; by the way, as you can often see here.
There is nothing to read between the lines from me. Refraining from misleading with your forum name would have helped you to be taken by the hand from the beginning in a way that corresponds to your level of practice.
As a donor design, I had most suspected a Gussek Haus – but apparently you "stole" the inspiration from Peter Büdenbender. This basis is particularly demanding for a beginner planner because of the (even if the term sounds a bit odd in Bavaria) rear "captain’s gable." When I do not put an architect in quotation marks, I always mean a freelance one, independently and transparently paid by the client – who necessarily starts at performance phase 1, i.e., never, ever inserts some internet floor plan into the plot or sets it elsewhere on foundations of dubious provenance.
A desire for a gable roof as the sole prior burden on the blank sheet is alright, provided it does not contradict the development plan. However, this alone does not guarantee a "D" within the meaning of the development plan, which always means a non-full storey (possibly also as a flat roof recessed upper floor). But with the intentional mishearing of reinterpreting the single-storey as a bungalow, you surely only wanted to tickle Yvonne ;-)
From your information about the plot and that the "land is available," I infer that you own a field of around 1050 to 1100 sqm, from which you expect to have about 850 sqm building land released through a reallocation procedure. If the procedure is already at least underway, the development plan should also already be in the consultation stage (and you would be wise to name it WITHOUT LINK here, even if has unfortunately not been active here for quite some time). But there are still four ladies and one slope-experienced gentleman here who can distill very discussable alternatives for you on this basis.