I built a house like this in US. The company is called Bensonwood / Unity up here in NH. It is not cheaper but it is faster and higher quality. From slab to dried in house in 4 days. Passive house level airtightness and insulation.

Wall assembly is zip->10 inch blown in insulation around 10inch I-Joist -> OSB -> 2x3 interior wall studs to hang your sheetrock off of and run utilities. (All pre-drilled for faster running of pex and conduit.)

You do have to do all the interior work after, though.