A booking platform connecting homeowners with structural engineers offering scoped, remote plan review specifically for smaller residential DIY projects would fill a real pricing and access gap, since most engineers currently aren't set up to offer a smaller, faster, remote-only service tier at all. Revenue is a booking fee, with the engineer setting their own remote consultation rate. The liability question is the one I'd research most carefully here, since a remote review without a site visit carries real professional risk for the engineer, and the platform's terms need to clearly define what that review does and doesn't cover before anyone signs off on anything load-bearing.