Use simplified custom shadergraph on import.

Hey, thanks for your work on UnityGLTF.

I would like to use a custom shadergraph that just has the most essential features to save on performance for a mobile application. That shader would just have DiffAlpha, Norm, ORM, and optionally an Emis texture. No fancy features and no texture transform.

Would this give me a performance improvement in comparison to the PBRGraph shader? If I inspect the PBRGraph, I can see a lot of nodes that would not be neccessary for my simple usecase (after stripping shader variants with the boolean keywords).

It would be nice if a different shader could be selected in the import options. My usecase is only editor import, not runtime. This would also allow for SimpleLit PBR approximations.

At the moment, is there any way to do this without extracting all the materials and manually assigning a different shader?

Thank you
Ludwig