What loan amount is realistic/reasonable?

2,500 EUR still sounds good at the moment, but one should consider that the planning is still at a very early stage. By the time a house is standing here, it will quickly be 2022 and then the 2,500 EUR will be relativized again. It will surely be enough, but probably a decent standard with 1-2 nice extras.

Also your notary and land registry fees. Although they are just peanuts compared to the rest, every little bit counts. With a purchase price of 103,700 EUR for the property and a land charge of 730,000 EUR (the equity will be used for the kitchen, basement + excavation), you are facing the following costs:

I would doubt 500 for a soil survey; 1,000 to 1,500 are more realistic.

Thank you very much for your input. I have incorporated the suggestions into the calculation.

I would also forgo the basement and plan a large storage room behind the carport/garage. By the way, there is not much of a price difference between a masonry carport and a garage.