It's a cool idea, for sure. Both for creating affordable housing, and for increasing the affordability of existing housing. But as others note, there could be

It's a cool idea, for sure. Both for creating affordable housing, and for increasing the affordability of existing housing. But as others note, there could be major complications at sale. Especially if the apartment doesn't increase the market value enough to cover the buy-out cost. Wouldn't it be more straightforward to just build pads and hookups for trailers? Or even for RVs? That'd be much easier to untangle at sale. And it'd probably cost less. Perhaps the startup could convert shipping containers to apartments. I've read about German ~gypsies that do that.