Yes, that all sounds good, but with us you have to build a house within two years, this is anchored in the purchase contract for the land.
This "building obligation" now exists in many municipalities and cities, but only for plots of land purchased from the municipality / city.
In such cases, the municipality / city then has the right to buy back the land if no building takes place within the deadline. However, this is a right, not an obligation! In times of tight municipal budgets, of course, one can also speculate that the land will not be bought back - but personally, that would be too risky for me...
When buying from "private" sellers, this regulation is rather uncommon.
Regards,
Dirk