Contractor licensing is a state matter, and in most states the trigger isn't whether you hold a hammer, it's whether you contract to have construction work performed. Hiring and paying subs on an owner's behalf is exactly the activity that pulls people into general contractor licensing in a lot of states, so before you charge for that arrangement you need a straight answer from your state licensing board or a construction attorney. That's the one part of this I'd get in writing rather than from a forum.
What's usually outside licensing: consulting and information work. Reading the ordinance for a homeowner and explaining setbacks, size caps, parking and owner-occupancy conditions. Pulling the zoning and permit history on a parcel. Assembling a bid comparison so an owner can see why three quotes differ by $40k. Sitting in the permit meeting and translating. The owner signs the contracts with the builder and pays the builder directly, and you're paid for advice and coordination.
On pricing, owner's representative and ADU consulting work is commonly billed hourly, often somewhere in the $75 to $175 range depending on the market, or as a flat feasibility study of maybe $500 to $2,500 that covers the zoning read, a rough build budget and a rent estimate. Some people charge a percentage of construction cost, which looks more like contracting and raises the licensing question again.
The piece worth thinking about early is insurance. If an owner relies on your zoning read and the city denies the permit, the loss is real money. Professional liability coverage exists for consultants, and general liability alone doesn't cover bad advice.
