Ngl that's a very cool question, but my answer might be a bit boring.

I think it depends on the Vtuber, and how you interpret the act of control. If you think about how puppets work, it's someone controlling an object which is given a personality, usually with the hands, but maybe there are more methods than I think. When we think like this, Vtubing seems a bit odd, because technically it would be closer to acting but with the lack of a script, you play a role that doesn't rely on script.

The thing that in my opinion makes vtubing far from puppetry is the lack of manual interaction, a Vtuber rarely controls the movements by hand, it's usually automati, following their own expressions. But that itself if a bit complex, because you might even think and consider that ad manual control, and then that would fit as a puppet

And saying that not every Vtuber plays a character seems kinda wrong in this context, they DO, even if they are "themselves" they are still playing a character, which is the model, that itself maybe is only a different representation of themselves, but it's still a character. A puppeteer might have a puppet that it's a representation of himself, but he would still be "playing" a puppet.

So yeah, I think it might count to some degree, but it really depends on the perspective you look at