Yes and no. Miku and other Vocaloids are made via voice clips from voice actors or singers, and then manipulated into actual words via tuning a recording on a DAW. The programming is all digital, and Miku herself is just an image used to sell said software. I think it can work on a smaller scale sort of thing (and Crypton is its own separate company). At most, Miku is used for a 3 minute song, and people can just use the software indefinitely. I think Crypton owns the rights, because the producers themselves do all the heavy lifting and make it and do all the work. Some artists do songs every week or two weeks, some do one song and never publish anything again.
I have no idea what Square Enix would ask for in rights to use "Aki Ross," or whatever her "character" would be called in other media after that. Who knows what and how that would work with the Japanese and English actors, what studios would want to incorporate it for its own projects, the rights involved, how it looks, how it sounds, etc. Maybe it's the same sort of thing where you have to loan out a license for copyrighted music or something, but then Square can decide how or what kind of stuff Aki would be allowed to star in, how much they would make from it. The level of individuality and personal flair used by Vocaloid producers is honestly a bit shocking. Some popular songs go into things like suicide, bullying, family abandonment, etc, rather than just some saccharine happy-go-lucky pop. It may not be so easy if a bigger company like Square Enix has to handle all that publicly. I doubt they'd want a digital actress showing up on porn or something...if they could even control that. Unless you have Ming-Na Wen record every possible word on the planet, I don't know if they'd be able to pull off fully digitized actress all the way. Bring her or a Japanese actress in every movie, it still ends up being Ming-Na Wen AS Aki Ross as such and such a thing. Probably too many degrees of mindfuck.
It's such a weird concept. Miku probably has to go through so many pieces of red tape to be used in commercials, anime, and other things. Trying to imagine a full-fledged leading role seems kinda insane. Then again, that's what AI and Deepfakes are kinda getting away with now. "Digital actress" is probably going to be a thing, but even now, probably too far fetched to be feasible.
"Evening caress, Always yearning, I must confess, The stars aren't burning"
Copernicus - Candlemass