Thanks for the information. We have considered talking to a lawyer about the 504, as well. My hope is that the outside evaluations and information can put pressure on the school accommodate him more. We also thought the same, that it was a last ditch effort because it will make negotiating with the school from now on nearly impossible. I don't want to sue them, of course, but he needs help, educationally and socially.
The psychologist we have an appointment with did mention that she has experience with education lawsuits, so it's nice to know that someone has that experience.
In a bit of surprising news, I contacted the people at PAGE (pennsylvania association for gifted eduation) a couple of days ago and to my surprise, they quickly got back to me. They even set up a zoom meeting with a gifted education director in PA for the day after tomorrow. So this person might help me figure out what to do next and give me some information. I'm honestly surprised they are being so helpful.