> very deep interests in things i was completely unaware that they existed

That's just a symptom of getting old. Young people always find stuff that baffles adults. When I was a teenager, Anime itself was like this - just being "into" anime was considered some kind of bizarre, obscure affectation by adults.

I think smartphones present real challenges (and I don't get how/why they're allowed in schools), but a lot of what you're describing is normal.