To my knowledge there is only one remaining true GT substantially separate (replacement) program in MA public schools, and it's on the South Shore, in Brockton. The remaining programs are pull-out enrichment- or in-class differentiation-based, with almost no routine acceleration programs that I could find. (Bedford appears to be an exception, with SSA referenced on their website.)

But there are two public virtual charters, one of which allows for acceleration via placement or (effectively) compacting (TECCA, a Connections Academy school), and has a defined GT track. You'll need some of the same supervision resources as for homeschooling, but not the instructional or curricular ones.

Another approach is to look at average educational attainment at each grade in specific school districts, as in this NYT infographic:
https://www.nytimes.com/interactive...s-how-your-school-district-compares.html
Inequity is, of course, the primary topic, but you can also look at these as informative with regard to school district expectations of average, which will tell you how many grade levels above nominal the typical classroom instructional environment falls. This appears to be up to three grade levels above the national average, in some of the highest-achieving districts.


...pronounced like the long vowel and first letter of the alphabet...