Build a new house, is the financial framework possible?

I have an offer from a major prefabricated house provider here:

145 sqm 1 1/2 storey, KFW40 including base plate (30cm excavation), ready to move in:

215,000€ + 11,000€ sample flat fee
+ 9,500€ single garage
+ 33,500€ plot (570 sqm)
+ 40,000€ incidental costs (outdoor facilities only 10,000€, the essentials in EL)

==
309,000€ - 4,500€ Bafa subsidy

I informed myself in a corresponding home builder group and they actually all more or less came to terms with these prices, of course the earthworks can still be really expensive, but that risk always exists...

I would at least not call it impossible to build a KFW40 house for 400,000€.

So move-in ready really means move-in ready with this provider, that is including floor coverings, painting work, and so on. Of course, the base price then only covers laminate, and partially even carpet.

I don’t know what is always included in such offers. That’s why my questions:

Is the kitchen included?
Is construction electricity + water included?
Earthworks? (Ok, you said yourself that it could get more expensive)
Surveying services?
House connections?

There’s easily another 30,000 (if not included in the price)

145 sqm 1 1/2 storeys, KFW40 including base plate (30cm excavation), ready to move in: