Pretty much, I use the shadow maps as a mask. So I tweak the shadows by using two gradients, one which will be used as the mask for the sketch lines and another for the lighting falloff. Sketchlines is blended using a color burn blend operation each (Directional and additional lines are kept separate), then added together. Shadow brightness is tweaked using a remap hooked up to an exposed float that can be tweaked globally using a shadow zone script MemeMan made.
The sketchline texture itself is applied to objects using triplanar mapping. Gives consistent results regardless of object size and UVs.
I use Amplify Shader Editor for my shaders, but this should be doable in Shader Graph as well.