I bought a lawnmower on craigslist and started putting up flyers. This set me back ~$75 at the time. I also did odd job painting and handyman jobs. I found a solid collection of clients fairly quickly and just walked around the neighborhood.
Encourage him to start a business, do all the financials, etc. and set up a scheme whereby you get a percentage ownership in lieu of rent. Step one might be management accounting literacy, specifically financial projections. For bonus points, demand a board report and get an experienced adult friend of yours to be a proxy board member for thorny issue resolution. You can start with non-monetized assets, like crops grown on personal property for repayment in kind. This way, capital outlay is minimal and real skills are developed, and there is even scope to involve others in exchange food and an education in business, without needing to crash-tackle tax accounting or financial services.
For example in France it was around 50% unemployment for 18-20 population before the virus. Must be worse now with the virus.
Why are people downvoting this? Teenagers in EU and Australia routinely travel around the world for jobs. Once they grow up, they become excellent hires at "real" jobs because of skills gained at such jobs.
Probably due to the travel ban being imposed against people from the US by those places right now.