I’m trying to apply a color to the material without affecting the texture itself. The goal is to ensure the texture remains fully visible while the color is applied only to the non-textured areas. I’d appreciate suggestions on the best approach to achieve this, whether through material properties, alpha maps, or custom shaders.
You kinda answered your question - if it’s just a flat masked color, you can add the color in shader, using the map texture alpha channel as an inverted mask.
In the built-in materials color is derived from:
color = <material.color> x <material.map> x <vertex color> x <instance color>
There isn’t really a distinction between textured and “non-textured” triangles, if any vertex has UV coordinates then they all do. But as @mjurczyk mentions, with a custom shader you could apply whatever conditions you need based on a masking texture.