South-facing plot 700 sqm, single-family house approx. 150 sqm, any ideas or input?

Idea, without having thought it through in detail: Access and driveway from the north, as there will be a garage there. Ground floor children's room, bedroom... In the basement then the living room, dining area and kitchen with direct access to the garden, placing the kitchen in the area that has a little less light due to the sloping hillside.

.. the uploading didn’t work, at least I don’t see anything.

I’m surprised that nothing else came here.

There was a worm in it. The plot measures 25.4 x 22.8m = 572sqm (to the northwest there is a rounding.

Are the 700sqm no longer valid? I’m a bit concerned, a rounding doesn’t make 130sqm, rather 13sqm. One usually knows the size of their plot. At a 10% slope, I first see and .actually. no basement. At 9 meters house depth that would be 90cm. But one could argue that you would want to level the garden a bit anyway, then you take what is higher and move it where it’s needed (soil). Then the house comes closer to the ground and thus the basement is justified, which then replaces the attic. Traditionally one would have a two-story building, since without windows on one side you need a bit more space elsewhere. The garage outside the house: no one wants it in the garden or the driveway there if it can be avoided. Also, the Renewable Energy Act basically prohibits this idea already. I’m of course also in favor of putting kitchen and living in the basement so that a terrace is justified and you can save yourself a balcony.

According to the construction site of the garage, no boundary development is possible. The variant with the garage/ CP in the SW is also not feasible.

Although the orientation of the house is not optimal according to the development plan, it is more acceptable due to the slight gradient.

Is the slope on the property also uniform further down? The information is missing.

The garage outside the house: no one wants to have this in the garden or the driveway there if it is possible otherwise. In addition, the Renewable Energy Act virtually already prohibits this idea.

Where does the Renewable Energy Act prohibit a separate garage?

According to the building plot of the garage, no boundary development is possible.

The justification for the development plan will have to brace itself.

Just for the crime scene villas of a single season of Rosenheim Cops, you would need several winning lottery tickets.

Those are exactly the kinds of sources I mean. During a creative phase, you don’t evaluate, you gather. Very often, you find out exactly what you like about the image and can determine that you can realize this aspect in a different and budget-appropriate way. It’s a shame for anyone who misses this opportunity. For most people, building a house is the most financially significant purchase in their lives. From my point of view, it’s worth looking a bit to the right, left, and inside instead of orienting yourself to what is standard. The standards are helpful for functionality – but life consists of more than just fulfilling "functionality."
Even if a "normal"-appearing house results from such a process, at least it is ensured that this expression of normality fits your own life.
For me, it was too risky not to engage with somewhat crazier ideas as well. But as the people of the Rhineland say: every fool is different.

No boundary construction is possible on the garage's building plot.

So what? If I take the, at least believable, 25.5 meters height, then a garage one meter from the property boundary is allowed. If you turn the garage into a carport, you can swing the car door in this airy meter. We have it like that too. But even if a garage is necessary, you can live well with the "lost" meter next to it – then the wheelbarrow goes on the rear end side or the trash bin next to the front end side.

Where does the Renewable Energy Act forbid a separate garage?

This was all related to the statement that the OP wants it inside the house and argues because of the slope, so the garage in the basement. So driveway in the garden, because it's a south slope: Nope! Garage inside the house: Nope.