Anyone flown skids as unaccompanied minors on international (or very long) flights? Any tips?

SS is almost 12 and it’s a 9 hour flight from New York to his destination. DH will be flying cross country to his connection in New York with him (to make sure it goes smoothly and because the airline was worried about what would happen with SS if the flight was cancelled and no one was there with him overnight).

SS has some mental health issues so this is really worrying me doing this but we don’t have a lot of choices and it’s too expensive for DH to fly with him the whole way. He cannot live with us any longer. I won’t let him stay in my house with my kids.

He’s refusing to speak to DH and me at all, so we can’t gauge what he’s thinking or what he might do.

We can’t give him something to knock him out like Benadryl or Tylenol PM because of the interaction with his antidepressants. I doubt his psychiatrist is going to give us anything to give to him when we won’t be there to watch or monitor him.

I’m packing a backpack for him to take with him on the plane that should fit under the seat so he’ll have access to it during the flight that has snacks and things to do. I’ve traveled a lot with my kids (the oldest is 3) so I’m not sure what I can put in there other than the obvious. I’ve packed some snacks, gum for takeoffs/landings and headphones.

He’s too old for coloring books but I’m not sure what kids his age would do on planes. He doesn’t like video games. He doesn’t listen to music. He doesn’t like reading but what are some books I could get? He’s a little behind in reading, so it can’t be too advanced but I would like to put a book in his backpack. Do kids his age do word puzzles or suduku? I want to look like we at least tried to send him with enough things to do.

The airline’s information about unaccompanied minors says they have some sort of activity pack they give kids, but it’s probably for younger kids.

There should be movies/in-flight tv but would a portable dvd player be worth it? I hate wasting money on things he’s not going to use.

He’s flown as an unaccompanied minor across the US multiple times, so this is something he has done before. But he’s never gone internationally like this before or on this long of a flight.