I didn't get the impression that DB was doing any major upgrades or repairs to OG's home. So far, there has been nothing found or revealed to indicate he had a business (website, business registration/filing, testimonials, etc.). I get the impression that he was hired to do odd jobs around the house (fix an AC filter issue, help a leaking sink, patch a crack in a wall, etc.). He had how-to videos saved on his YouTube about things like how to tile, installing a telephone socket, plumbing drain problems, etc.
This is why it's so interesting to me how he came about to work for their household. People like that always come via reference or interpersonal relationships (like hiring an off-books housekeeper, etc.). Likely, the people who did hire or recommend him wouldn't exactly be willing to volunteer that information now, but I am sure they are out there.