Any elementary schools good for kids with ADHD?

I understand public by default is better, but not all. We’re in the 1st grade public school now and they haven’t provided any support all year, even though we have 504 plan. They started “working” on IEP in January and only now everything got sent to the district and we should get some update during the summer. The excuse that they are understaffed and now they suggest holding him back a year. Even counselor said if there is no IEP we shouldn’t hold him back since it will be repeated cycle. So… what schools are actually kind and supportive of kids with severe cases who just need some attention on getting ahead in their development. My son loves music and has an ear and voice for it. Maybe some musically inclined schools or stem would be helpful.