First the land, then the house years later?

The bank of the property has the first priority. You are then dependent on them for the home loan, any other bank will demand security surcharges.

Let's assume for a tiny moment that banks are not all honest: then one could see the risk that they would make the loan for the property non-performing in order to push it to one of their other customers. Of course only if banks were not all honest. But thankfully that is purely hypothetical

Only without building obligation. But if you already can't build now, why not buy?