Modular house, wooden plank house, or solid after all?

There are "enough" banks that are already reserved for a "finished 'prefabricated'" house. The two providers you mentioned are even more so not house manufacturers at all, but from a banker's perspective pure building material suppliers. For kit houses – where no warranty applies to the product (= the loan security) – I don't see any banker looking on enthusiastically. Moreover, the development plan must also allow wooden facade houses, because such houses are not suitable for plaster or brick cladding. And: go to a health food store / a natural foods shop and compare the prices with a normal supermarket. Then you will get a feeling for what such houses will have cost "turnkey" (or do it the other way round, and ask a solid construction builder for a shell construction offer). The misconception that a way has been found for an especially affordable house will quickly be dispelled. Looking at the wallpaper-ready square meter, you will pay about the same with a shell house from a "prefabricated" house manufacturer.

Regarding the idea of the "module house," I have already said here repeatedly that this "Columbus' egg" has regularly been considered a solution for a hundred years but has never really caught on in implementation. Some dreams simply do not last longer than the effect of the hemp baked goods under whose influence their genius was "recognized" :)

maybe buy a plot of land, put a used garden house on it, later to be used as a shed. We had a 40sqm bungalow on our plot, wooden half-timbered, for self-dismantling at classifieds for 500€, it went quickly. As a transition, a lot is possible, camper van/wagon, circus wagon, etc. and you see the path of the sun, hear the neighbors, airplanes, roads, birds