After the first 2/3 of your post, I would have thought you were building on 1000 sqm or more. Then only 460 sqm – I guess everything is relative.
I felt exactly the same. We are also in that range, we were actually searching for 500 sqm - 600 sqm. As someone who moved from Lower Saxony to Franconia over 15 years ago, you have no chance with all the local native models. The price per sqm here is now in the four-figure range close to the city, in the commuter belt 400€ and up. You are glad if you a) even find one and b) can afford it. Logically, everything is through real estate agents. Building gaps with old buildings are even rarer. 400 sqm is nominally actually too little for me, but it still depends a bit on the location and neighboring buildings and what the architect conjures up there.
Advantage of a smaller garden -> less gardening work [emoji6]
Advantage of a new development area especially for young families: quick connections, many opportunities for the kids.
Crazy world in the end. My sister built 40 km southeast of Hamburg three years ago, about 5,000 inhabitants. My brother-in-law would have liked 500-600 sqm, the municipality says “there is nothing under 800 sqm.” So 870 sqm, price: 78,000€
That only works for us if you really move far out, roughly 80 km into the middle of nowhere and a village with a milk can and streetlight...