We work with local builders, providing the fully designed/engineered packages, with ALL materials needed to build that specific high performance home.
You are right, trying to do this in a fully centralized and detached from community is not workable. We think our take leverages the strengths of both parties and allows us to do this much more broadly.
Regarding technical challenges, we engineer our SIPS shells for seismic by default and can accommodate most snow loads (Tahoe project in the works). HOA's are a PITA no doubt, but urban infill is possible and green field is always going on regardless.
From floor down is all local and must be adapted, so not so turn key there But hey, can't have everything.
Gotta run, but like your approach. Maybe more later.
The homebuilding business is about controlling land. The big boys option hundreds or thousands of buildable lots a pop. In a metro area, that's still a drop in the bucket. Controlling that many lots justifies a sales center, in house financing, and creates one stop shopping.
Land converters, those who subdivide land into residential lots, usually prefer to sell to home builders. It lets them deal with professionals and let the homebuilders who buy lots do all the high touch consumer sales or take the risk of building on spec.
The consumer oriented home design business is likewise bimodal. The big spike is price sensitive: it's $500 online blueprints. Everything else is high touch. Money is no object clients are both rare and tend to be high maintenance. They must be cultivated socially...church, civic club, university homecoming, whatever. They have options...those with buildable lots have even more, including just sitting on it.
Regarding taking deposits, there's almost certainly going to be contractor licensing laws in play. In the best case both a state homebuilder license and a local business license. In the worst case, a local homebuilder license and a local business license. Local homebuilders' associations are fairly active. They will report unlicensed competition.
Legally, laws regarding construction are far more entrenched than those surrounding other disrupted industries...they go back to Hamurabi. Unlike a taxi or a rented room, construction is visible and can't be moved. The local fire marshal has seen people die. The local council woman wants to protect property values by preventing shoddy construction. Local home owners, want to keep construction out of their backyard, unlike an Uber they're not likely to become late adopters...it comes back to location.
Technically, the amount of variation nationwide is massive. There is a combinatorial explosion of wind, seismic, snow, ASHRE, moisture, and aesthetic requirements and preferences. That's before touching soils...every site is potentially different. At best there are local and regional requirements regarding radon and frost depth. At worst, there's rock to muck on adjacent lots.
Anyway, it's an interesting problem.
Good luck.