Is the land use plan binding? Possibly a building window in forest area?!

"Bauerwartungsland" in the "Außenbereich" also seems a bit suspicious to me.

No; that's a typical case of land speculation.

If the buildings marked on the map, which are surrounded within shouting distance, do not belong to different districts and/or are all used for agricultural purposes, I can't really imagine that. Some neighboring plots still look like they are intended to be used as fields based on their layout; the row where you want one would be suitable for beekeepers or allotment gardeners. "Land designated for future development" in an "outlying area" seems a bit odd to me.

Unfortunately, I forgot to ask why so many other people could have built there. But he was very sure in his assessment and said that people often ask questions about that area. At times there have even been lawsuits, all without success.
That would only become building land if the responsible municipality decides so, and supposedly they "currently have other problems."

Well, it could be that someone will make a lot of money soon if they are lucky. For us, it’s just too risky (especially since there’s only one representative commissioned for this municipality and he thinks nothing will come of it), after all, money doesn’t grow on trees....

It was a nice dream, but the price and the duration of the listing (everything else is offline two days later) already pointed in this direction...

To me, "Bauerwartungsland" in the "Außenbereich" sounds a bit strange.

But it is very German. The designation as a residential building area in the land use plan already makes it Bauerwartungsland. Wikipedia explains it better than I could.

It would only be building land if the responsible municipality determines it

At least it has already been determined that way in the land use plan. But it has already been said that the way to raw building land can still be very long.

People often inquire about that area. At times, there have been lawsuits, all without success

However, there are no clearly defined criteria for the boundary between inner and outer areas, so in most cases a legal dispute is pointless. The district of Stormarn has a very nice explanation with examples and court rulings on its website under -> Service -> Lexicon (or try the search function). The property is only for patient people who don’t know what to do with their money.

Wikipedia explains it better than I could.

I have my doubts about that, but I'll be happy to look it up.

However, there are no clearly defined criteria for distinguishing between inner and outer areas,

But a quite common interpretation is the imagined string around the buildings of the existing settlement - obviously not counting privileged (e.g., agricultural) buildings and not crossing district boundaries. In this sense, "surrounded by settlement" and "outer area" exclude each other. Can one say, no, on Fridays at full moon this logic does not apply?

But the interpretation with the imagined string around the buildings of the settlement stock is quite common

Yes, that's correct. However, opinions differ regarding the term "settlement." In the present case, I also find it difficult to speak of contiguous development, as the undeveloped plots predominate. The area is highly fragmented and urgently needs an urban planning concept. But who is supposed to draw it up and who is supposed to pay for it?

not crossing district boundaries

The district boundary is only a cadastral ordering criterion. If it is not identical to a political boundary, it can be easily shifted (if it is even necessary) and has no planning law significance by itself.

Can one say that no, on Fridays at full moon this logic doesn't apply?

It happens because the shades of gray in the gray zone at full moon in December shortly before quitting time appear different than on a sunny midsummer morning. I have experienced that the same employee assigned the same plot sometimes to the outer area, half a year later to the inner area. Lucky is he who has the favorable statement in writing.

Where is the logic here actually? Why should a municipality or an investor designate an already sold plot of land as a building area? IF anything, the municipality would want to make money from it and buy the land from a farmer beforehand or already own it. The investor is very similar in mindset, as they achieve their profit through the necessary work (development costs, roads, etc.) in the land sale. So why should anyone suddenly want to develop completely unrelated plots, even if these costs can of course be passed on to the owner? However, with just one house, that quickly becomes really expensive. Overall, the whole thing seems very much like a lottery to me. The land situation with you must be extremely tense, and real estate agents are trying this way to find some idiots who buy a piece of forest at an exorbitant price.