Ok, there is a big question mark missing. Earthworks are a cost driver and are higher for bungalows than for other houses.
The climate slab is an all-in-one. Without screed, filling, and so on.
Get informed about impact sound (not from the upper floor, but so that you can hear the children running in the children's room from the bedroom).
There was already a thread about strong noise transfer from the neighboring room. The screed was not installed as a floating screed.
Who builds the base slab? The house manufacturer himself or a subcontractor.