I know the answer only helps to a limited extent, but that depends a bit on you. Do you prefer parquet or is laminate enough, do the floors have to be floorboards? Should the doors be flush or with a surface-mounted frame? Is DIY store sanitary ware sufficient or should it be Villeroy & Boch with Steinberg fittings? Fireplace desired? Panorama or Swedish stove? Kitchen included?
1700€/sqm is more of a basic standard, 2100€/sqm is a good standard, meaning parquet, decent sanitary equipment, panorama fireplace, no flush doors. If that can even be said in general...
Personally, I wouldn’t go below 2000, with 2100 to 2300 you probably have a good starting value, but still plan some buffer (about 10%) for miscellaneous/unexpected costs. The "annoying" thing about building a house is, the saying “Appetite comes with eating” is true here too... so having some “play money” isn’t bad, otherwise frustration comes if you’ve budgeted too tight. And building a house should be fun [emoji6]