An option to be able to make characters rendered with some sort of customizable Cel-Shading would be wonderful & open up many new options for making characters. Whether the shader would be universal or per-character, I imagine it would need to be adjustable to look right for certain characters or environments. I also imagine that the eventual transition to URP would make things like this more feasible, so obviously this is no priority, it would just be a nice addition if possible.

If this is already somehow possible when creating a character, then apologies. I know you can change character's Material Shader from PBR to SSS, but I don't think you can emulate the Cel-Shaded style with these, as far as I know.