Loan amount - What is achievable?

Thank you for the quick response.

That's correct, it says so there, which is why I asked.

Because if I do the "pre-check" on the kfw-Bank website, the first question is:
"Is your new home as of the key date the only residential property you own?"

Next to "as of the key date" there is the information:
Your situation on the day you received the building permit for your new home applies.

That, in turn, would speak in favor, wouldn't it?

"Is your new home the only residential property you own as of the relevant date?" The information next to "as of the relevant date" states: Your situation on the day you received the building permit for your new home applies. That would argue in favor, wouldn’t it?

Does that mean you are moving into a rental apartment temporarily???

Either I would agree with the buyer to be able to live there rent-free for a while after the purchase (in exchange for a purchase price reduction), or we would temporarily move into my parents' house.