Floor plan of a single-family house with approximately 150 sqm on a rear lot

I couldn't warm up to the east orientation. The garden would be too fragmented for me. (But if that doesn't matter, just rotate it.)
Attached is another sketch based on the original draft: north is at the bottom of the plan.

Do you have to build way too many streets here? Yes! Otherwise, the carport in the west would block too much light.
If one could warm up to the I of the open space, the carport in the west would be an option again.

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Well, presumably all of this is an absolute disaster because, to quote the OP's words:

...that's exactly why I say you have no idea what you're talking about.

Thank you for the inspiration. I am 95% sure that the city will allow me to pave half of the property. Our city is absolutely committed to preventing soil sealing. While other cities are debating whether to create more parking spaces, here the discussion is whether having zero parking spaces would even be good.

Unfortunately, there are no interior dimensions provided, but I would estimate that with our furniture (corner sofa - yes, the plan shows two because the program crashes when I design a corner sofa, dining benches and no chairs, etc.) it would not work. Also, all the interior doors in our plans are 1m wide, and the walls that have a door would then be 1.2m. I believe that is actually not stated anywhere.

Ah yes, I would not dare to use the word catastrophe. There are certainly things in your proposal that I would never build and others that I would. And that’s the point. If I now tell you that the bathroom upstairs is simply way too big, that I would never put a washing machine upstairs, etc. etc. etc., you would want to tell me that’s how I need it.

What is clear, though, is that the upper room doesn’t really benefit from the bay window. It simply doesn’t matter in the room’s use if it has half a meter more, BUT the living room definitely needs it if you put the sofa in there, because then you can walk past it. Does anyone have any idea what extra costs that causes for wooden houses?

Does anyone have any idea what extra costs this causes for wooden houses?

There is no fixed surcharge for bay windows. There is only one price for the house with a bay window and a different price for a house without a bay window. Different house, different roof, different statics, different construction grid .... I could imagine a difference between the prices of 10-40k€.

I assume you mean "not" to seal. I found the arrangement of the carport by quite good: https://www.hausbau-forum.de/threads/grundriss-efh-mit-ca-150-qm-auf-hinterliegergrundstueck.45070/post-621499 But I would make it at least 4m wide to leave space for the front door and to keep the turning circle large enough. I would only use the west side as a parking space and turning area.

The thing with the washing machine in the bathroom was probably a misunderstanding. I thought your laundry basket tower was a washing machine tower. The space in the bathroom for that would simply be swapped out for the laundry baskets + a laundry chute would also make sense.

For the 2nd bedroom, you could say whether there will be a central ventilation system. With that size, it’s mainly about the air for sleeping at night. The keyword is CO2 load. But I think everyone understood that you would prefer a smaller room.

In the whole arrangement, the question still arises for me as to whether the neighboring garage will really be built like that. It was sketched out in #38, and with 11m between the house and the boundary, there are only about 5m left to maneuver in and out. But if the neighbor now builds his garage differently, the "optimal" position of the carport will also change, and with it the position of the house. The situation is not quite simple. When is the neighbor building his garage?

Any idea what kind of additional costs this causes with wooden houses?

There is no fixed surcharge for bay windows.

As a monetary amount, I couldn’t answer that, only in principle (and this has less to do with "wood" here but rather with "panel construction"): 1. a bay window basically turns a single-panel wall into a three-panel wall; 2. the consequences in the roof structure are the more expensive part.