I’d always defer to MostHost_LA but my intent was to be able to make a mask, which you seem to have done, and from there…whatever. It’s essentially the ‘snow-mask’ using the normal-map and WS-up, but you can do whatever besides just tinting.
You’re never going to be able to fake lighting in the shader 100%, but you could brighten the RGB, add a dash of specular, whatever you felt you needed to do for the visuals. What I mentioned above was more just to isolate the area one would be doing those things to.
Lighting is handled by the engine ultimately, and what you can do in a shader won’t know about the totality of the world around it, so you won’t 100% be able to faithfully reproduce that lighting the engine would otherwise be able to do for you. Anything past the mask is just style, dependent on whatever you feel you need to do in your project.
If I implied you can just-reproduce lighting in the shader, not really, so my apologies for any confusion.