We have the main eye material and a duo eye material.
Material Update for other characters in Progress
I have recently upgraded the master eyes material for my new character Aren, some of the options below might be missing in some of my older characters, but I will update the materials and eye mask textures for all characters hopefully before the end of February 2024.
The duo eye material uses the vertex color of the eyes to separate the left side and right side. Then it uses the eye mask input to tint the area specified by the mask.