@JUHDUH Sorry for the late reply, I was on a short vacation.

Some helpful forum threads are referenced in the spine-unity documenation section here:
https://esotericsoftware.com/spine-unity#Shader-Graph
If you want to write your own shaders to copy existing Spine shaders functionality (either manually or by using Shader Graph), the basic rules and caveats are listed here in subsection Caveats when using non-Spine shaders or visual shader editors:
https://esotericsoftware.com/spine-unity#Writing-your-own-shaders