Backstory: I was browsing around for a sketchup tutorial and found a sketchup specific tutor site: https://www.sketchuptutor.com/. As that's all the site does, I found it rather appealing and they had some impressive examples. If this site works, you could find another niche and build a similar site.

The Idea: A niche tutor website.

Deep Dive: Corner another niche like sketchup with a specific tutor site. I've often wanted to get better with InDesign but I've never took the time or found a course that is interesting enough. You would have to pick a niche that you're proficient in and doesn't exist... you could corner the market.

Validation: https://www.sketchuptutor.com/ seems to be doing well, I found it organically.

Monetization: You would charge a rate for yourself in the beginning and as you hire other workers, you would take a cut from their fees.