Have you heard of https://www.davidsongifted.org/ ? They will help lobby the school system, or help you find other resources. And also get your kid connected with other kids that are intellectual peers as well as age peers. Also, for math specifically, check out https://artofproblemsolving.com/

We eventually home-schooled. At some point, you look at all the time you spend lobbying school administrators and selling band candy, and decide it takes less time to just home school.