I'm just going to ask the question OP. Are you absolutely certainly that your DS isn't autistic too?
You say he's sociable and struggles academically - but also isn't keen on meeting up with friends in half term etc, which suggests he's not as sociable as described?
I have 15 yr old twins, also a boy and a girl. Both are autistic too so I completely understand the challenges, including finding suitable activities. My two also very unreasonably like to do very different things and have wildly varying needs. So inconsiderate of them 😂
I find teenagers need space, to know you're there when they're ready, and to know that they're loved even when they might be pushing you away. I read on here once that you need to keep on loving your teenagers throughout these difficult years,and though they might seem distant and indifferent, this is when they need your love the most!
I also think that our generation of parents is a bit of a limbo group. We use tech in our daily lives but weren't completely absorbed by the digital world when we were growing up - so we have been conditioned to think of screens as "bad". And you'll certainly see that view a lot here on MN.
I don't necessarily agree. Children can develop skills through the use of screens and it can be a way to stay connected socially. People talk about screens being "bad" but often they're not entirely sure why. Screens actually provide loads of benefits - and I say this as someone who prefers paper books, not screens!
They're particularly helpful for neurodivergent children.
Having said that, I agree fresh air and exercise are important. I just think that you might be giving off an air of disapproval about gaming and screens, and if that's the case, it will drive a bit of a wedge. Like a PP said, it's about getting interested in what they're interested about. And at that age staying in a treehouse might be deeply unappealing - but give it 10 years and they'd enjoy it again! Teens are funny years as the DC are finding out who they are while their hormones are going crazy. They're often desperate to avoid anything that seems uncool.
We enjoy movie nights at home. Me and DD craft together - not joint projects, just sort of being in the same room doing the activity. Might have a TV show on in the background. Just really low-key activities that I know they enjoy and don't seem forced.
You talk about their dad going carting with DS - by any chance, is he the "fun parent" and you're left with the drudgery?