Oh bless his wee heart, sitting still and listening to instructions is so boring and HARD for a lot of children,
With the issues you describe and the move, he has a lot to cope with.
My son had similar problems if I got a lot of help from an OT. School not great at first but after a meeting with the principal things improved a great deal.
I put a lot of effort into helping him develop core strength (swimming, climbing, trampolining) as that helps them to sit still; we had finger strengthening exercises to help his writing, cool off strategies, brain food diets, audio books (as reading was hard for him), and really just a lot of trial, error and occasional success
He's extremely loving and will curl up with the cat for ages, and responds very well to route, physical exercise and hands on tasks (baking, washing up fixing, board games).
Now 9 and a different boy - steaming ahead academically, highly involved at school and in sport, plays 2 instruments and has lots of friends.
Best of all he has gained insight into his challenges and is able to identify his needs (I need quiet time, I need a hug).
Socially he can still be immature when under pressure (noisy restaurant, lots of guests) but so
much better than 2 yrs ago.
So keep doing what you're doing, remember there are lots of kids and parents struggling like you, and have faith that things can get a lot better.