Some Wander Over Yonder fanart I’m working on. I hope they get a 3rd season.
The rig is actually quite simple so far. There is a hidden icosphere that acts as a shrinkwrap target and the eye itself is shrinked onto it. As you can see in the video, the iris and pupil are controlled by simply scaling a bone.
Source
Obviously he is a very expressive 2D characer so while modeling him will probably be easy, the rigging may not. Which is just the way I like 3D.