Nyjah Huston says he could've been racking up those Olympic medals for more than a DECADE ... telling TMZ Sports he would've been ready for the Games at age 11!
Of course, skateboarding will be in the Olympics for the first time ever in 2020 ... but if it had been a thing in years past, Nyjah says he woulda been a serious contender while he was still in MIDDLE SCHOOL!
"I started skating pro contests when I was like, 11, and I was going out there on a competing, winning level .