OP, my initial response on reading this was that these things are just about his interests/personality, and have no relation to his sexuality.
However, in honesty I remember a conversation with one of my best friends, a gay man, who told me his mom knew he was gay when he was a toddler. I asked him why and he said something like, "I used to dress up in high heels and mince around in her feather boa". While there is a facetious element to this answer obviously (his humour is like that) he was also adamant that there was a flamboyant aspect to his behaviour as a toddler which enabled his mom to work out that he is gay.
And the interesting thing is, he is NOT a flamboyant adult. His dress sense is relatively conservative and certainly masculine; he works in an industry that requires stereotypically "masculine" attributes such as physical courage and endurance (please note I say TRADITIONALLY masculine - I in no way condone the view that these should be associated with men); other than a gentle, kind nature and an unusually tidy house, there is nothing about him that would not be seen as "typical bloke", and on a few occasions other friends or family who have met him at social occasions have expressed surprise when I later mentioned him having a male partner.
However, he is adamant that it is just the sort of thing OP mentions, that enabled his mom to work out his sexuality at a young age.
My now adult stepson was similar as a child, and is gay, and STILL keen on personal grooming, sparkly stuff for his room, and other traits people associate with "girliness" (tho he also likes cars and football, and other "boys stuff", too. )
His dad once told me about some weird bit of research he had read that suggested birth order effects sexuality in boys - something to do with the amount of testosterone passed on by the female. But though I am no endocrinologist, it's never been my observation that gay males lack testosterone, and I just wondered if the whole thing was a bit of a homophobic fabrication.....
What do any of these ramblings tell you? Fuck all really, based on my sample of two, except that you could be right, OP.
But the main thing is that it doesn't matter in the slightest. You may not know for a while. He may not know for a while. (Though I remember being conscious of my sexuality from a very early age. The two guys I mentioned above have always told me they felt the same. But many people also don't).
I would try to avoid stereotyping him in any way if you can. His tastes in terms of pastimes and interests will change and keep changing, as you know, being a mom of grown kids already. Make sure he always has the space to do that. People like to pigeonhole unusual kids in my opinion - he needs to have the freedom and space to follow more conventional pursuits when he is older, IF that is what he wants to do ......