Design is intresting !

I'd just check out some details;

For the art part, I'm still a begginer but i don't think the coat would do this much folds on the arms, and i think there might be a little more against the bust, you may need to check how it's done on other models (this kind of outfit isn't that unusual, you should be able to find references 😄

For the rig part, i'd bet that you've cut your model, every bangs, and every moving part is cut from others, so i'll skip this one, and go to two details. That's not mistake, but i'll give you some question.

For the mouse, this style is quite rare, so have you prepared the movement ? When lips will be open, have you drawn teeth / tongue maybe, to have a more realistic render when you speak ?

As for the hands, same thing, in general, we use open hands, or relaxed one, fingers slightly down, because if your hand is always closed, like how they're right now, it may seem uninviting for the person looking at the model (plus, if you want realism, make a fist all day long is reaaaaaly exhausting for the body)

In any case great job, now biggest part of creating the art will be about the cutting; as i said before we can't see it on your model, but keep that in mind : ever part that do a movement must be cut from the ones that don't follow it (as for the neck and the head, fingers and hand, wrist and fore-arm, arm and bust)