Not sure that fitting a bathroom or kitchen is the difficult part of the concept, though.
It reminds me a little of an old Grand Designs episode. [0] Different, in that (AFAICT) the 3D-printed house isn't designed to have high thermal mass (the 'earthship' concept) but it gives an idea how a fully-functional house can be crafted from a lot of earth and work quite well.
[0] https://www.granddesignsmagazine.com/grand-designs-houses/97...