I used the opportunity to teach myself Substance Designer to create a Texture Generator / Configurator for my Charactrer's eyes :)
https://twitter.com/zorryn_art/status/1663875871395004417
What an awesome tool!
The compiled *.sbar file is only 10kb in size and generates a bunch of textures as needed:
Diffuse, Normals, Masks for part of the eye.
But the fun doesn't stop there: The shader is completely customizable in color shape and size, too!