I knew a few 16yos when I went to uni. All lived in halls and finished the course having done well/exceedingly well.
Two if it hadn't come up in conversation, no one would have ever known. They didn't stand out either physically or in maturity.
One of those was a true scholar. English was, I think his third, or might have been fourth language. He did his degree in two years, gaining enough marks that you could have split his papers in half and both would have got a high first, and then chose to do a totally unrelated degree (kind of opposite end of the spectrum unrelated!) in his third year, which he also got a first on. All of that while appearing "normal" and doing lots of other things. Someone mentioned him a couple of years ago and he's been a professor for several years at that point.
The other had skipped a year at school and then moved countries and accidentally been put into the wrong year, so ended up two years above. He was average on the degree course, if I remember rightly. He did struggle when people were living out and ended up going back and living back in halls at his request, but I don't know why.
One did stand out. He was tiny, and only began he growth spurt when he was nearly 18. He also didn't really mix, although when he did, he seemed to enjoy it. He was very quiet at all times, and I don't think ever sought out doing things with others. I haven't googled him, but I wouldn't be surprised if one day he appears in the news with something amazing.
I seem to remember in one of the few conversations with him he mentioned that at least one university had told him they would only accept him after a gap year.
There may well have been others I didn't know about, but those were ones I did know! I don't think any of those three regretted it. I know the first two didn't, and I don't think the third did either.
I know you've said he isn't interested in the social side, but I do think you have to think about that. When I was at uni, there was very little checking of ID for example. But he could be in the position that if he is making friends then they're going off to things he can't go to, so it becomes self-fulfilling in its way.
I had a teacher at my secondary who went off to uni early. He told us that he thought it was great and everything was perfect when he went-but he really regretted it later. He realised that he had missed out, especially on the socialising, and he felt he'd have been better to have waited. What if those extra two years waiting means that your ds matures enough that actually the group projects will work better for him and he will want to socialise?
The other thing which I'm going to put out there is that a 16yo is in that state where they're not a child, but they're also not an adult. Let's say, as it's music, he joins an orchestra/band/music group. They're going to tour. They may not be happy (or risk assessed) to take a 16yo without supervision. How would he feel if he missed out on that sort of thing? Or you have to go with him in order for him to go?
And lastly, I don't know what they ask for to get into conservatoires. But I do know that most universities want something in terms of A-levels or equivalent. Yes, music exams (and dance) at the top end (which I assume he has) do get "points" but a distinction level 8 for music is only 30 points, which is the equivalent of about a C. They'll normally assume you're doing three subjects, and he may have more than 3 instrument/theory exams at that level, but, I don't know about for a music degree, but the persona I knew who used that was told she could only use one of her music exams towards the points. So you need to look into the requirements for the course.
I don't know about conservatoires, but I've looked at Birmingham, for the simple reason a friend's dc has that as his top choice, and they say:
"Students usually need two A-level passes (or equivalent) and Grade VIII Distinction in their instrument of choice".
Look at the ones he's interested in, and phone the admissions office and ask.
They're all things that you might want to look into and consider.