With some modern design concepts (e.g. leaving plenty of plenum for unanticipated future cabling/plumbing needs) I think you could come up with a very pleasant place to live, just at probably quadruple the price.
Is anyone building stuff like this today? Or would this have to be some extremely custom stuff you need to research and act as a contractor managing a bunch of subcontractors?
> Is anyone building stuff like this today?
can it even be done while satisfying modern building codes and energy efficiency requirements?
They are built all of the time. Invest in good windows, metal roof, and good drainage and the house will be around 200 years from now.
The farmers I worked for as a teenager revovated their Dutch built barn (ca. 1660) into a home. The secret is keeping the water out.