Is there a way to possibly do this / not difficult to implement?
By multiple materials overlaid in one object/node, I mean several materials can be on an object at a time, I don't mean by different faces having different materials, but each face can have multiple materials in a way.
Ambient Occlusion map
Emissive map (what parts of the texture should emit light/ignore lighting)
Specular / Ambient map (instead of one colour to pick, those options pick colour from a texture, this same goes for Emissive map)
Overlay map (Texture is stacked on another texture)
Transparency map (Alpha channel in a way, but can be edited/loaded separately from main texture and combines with main texture's alpha channel)
Pretty sure most of these could be done using shaders, I am not sure though as I haven't messed around with shaders yet.