Costs of a real partition and subsequent development?

Thank you for the detailed answers. Overall, they have helped me a lot to get a feel for the topic. One final question. Isn’t a [Pfeifenstil-Grundstück] also an aspect that tends to lower the price? Because I did some more research and the length of the supply lines from the street to the house has a very significant impact on the ancillary construction costs. A house on the street has significantly lower costs in this regard.

Isn't a cul-de-sac property also an aspect that tends to lower the price?

Not in the foreseeable future, since such rear lot parcels are currently (and even increasingly) more the norm than exceptions on the market. And as mentioned, a genuine private street connection is already "superior" compared to a GFL corridor. By the way, cul-de-sa[c]l[/c] is spelled with "e", it has nothing to do with level(s) or taste.

Is a piping-style property not also an aspect that tends to lower the price?

Just a note: if you don’t buy it, someone else will. It can happen while you are still writing here.
You should be somewhat decisive (meaning know what you want) and not think you can negotiate the price a lot.
In the end, as a back plot owner, you have it quieter...

The sellers often don’t care who buys... they want an unproblematic buyer as quickly as possible.

I do not have that impression. It seems to me rather that this plot of land has been for sale for about a year. The viewing was on a Sunday. If it were so easy to sell the property, there would not have been a viewing on the weekend. It is currently difficult to sell real estate, at least in Hamburg, where prices are different from elsewhere anyway. Properties are regularly reduced in price if you follow the major real estate portals. We are now back in a buyer’s market because most people cannot afford the prices with the current interest rates. Since the hoped-for interest rate cuts are probably not coming, the pressure on prices will continue. I have all the time in the world. I will not spend 0.5 million euros in a rush. If someone is faster, then that person is welcome to have the property. I will inform myself well before putting that much money on the table.

Sellers often don't care who buys... they want a quick, hassle-free buyer.

I can well imagine that the desire to stay in the familiar house without the drawback of having an oversized garden is the top priority (and just a little extra income in old age only the second). That’s where I would also rather apply leverage: for many sellers, payment methods other than all cash (now) are much more attractive.

We are now back in a buyer’s market because most people cannot afford the prices with the current interest rates. Since the hoped-for interest rate cuts will probably not happen, the pressure on prices will continue.

That has only a rather indirect and marginal connection to interest rates. We are back in a buyer’s market because the position of the remaining buyers is getting stronger when their competitors are called back by their banks. When the overbidders suddenly "die like flies" and only the market value bidders remain in the game, sellers’ dreams don’t fly so high anymore. Conversely, their pressure to sell remains stable (they are not getting younger, and the garden remains too big for them).

Isn't a pipe-shaped also an aspect that tends to push the price down?

Theoretically yes, practically such plots are the only ones still available in central locations for single-family homes. I see the greatest sales pressure on the seller only if the money is needed promptly. Otherwise, a garden can also be allowed to grow wild quite cheaply ;)