definitely intentionally ND, given how his dad and neighbors were saying "he's like *that*" and were saying to take him to the hospital/get him checked out. all we really saw was hyperfixation and not following "rules" (ie going to playground during classtime)--he was always interested in others, ie making eye contact and interacting with his mom fully, so more likely ADHD, though i think the author was going for autism spectrum.

im nd and i heavily relate to him, i wish i could know if author makes him a fellow nd intentionally, because the way his backstory is explained screamed autism to me