Morphs are where either the shape of the head or the proportions of the UV map change, right?  Just making sure I have my terminology correct.

I was trying to think of something a bit simpler than that.  Did you ever watch RWBY when it first started?  It was animated with Poser back in those days.  And what they did for the faces was more or less create a layer on top of the face that they animated expressions with. I'm thinking the way they did it was to basically create two figures, and superimpose the second figure with the facial expressions and lip flaps over the first body model, and select "do not show" on everything for the second model except the facial features.  It's why I thought the Little People would be a good starting point - I would only need to figure out how to move two dots for eyes and lip flaps.  But that's a guess on my part, I don't know how they made the show.  Supposedly, not counting voice and mocap, the animation team consisted of only four people.  Once again, though, that was way back when.  I think they switched to Maya in Season 3 or 4 (and the models they started using didn't have that...uniqueness, I guess?...that the Poser ones had.