One of the great things about Massachusetts is that nearly every town has a Unitarian and/or Congregational church, often at or near the town common, with a rainbow flag or sticker and other indications of being welcoming.

But that didn’t tell you about the schools. I don’t know whether it’s possible to get a record of which high schools had groups marching in the pride parade (back before the parade organization fell apart). Maybe BAGLY or PFLAG can help you find the most supportive schools.