I want my object to have glitter that is responsive to the light, but part of the object is matte. I would implement it by separating faces in the mesh and having multiple materials, but I need the user to be able to dynamically apply this texture and decide which part of the object should be glittery or glossy.
Yes, you can control these features with a combination of some of these texture maps:
Sure, for example, dynamic roughness with noise: White Gold (Reflector, custom geometry)
But anyway, I vote for textures