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I’m moving the thread to a more appropriate category (Resources > Tutorials, Tips and Tricks is for those only, not for asking support)
In respect to your question, you need to pass some attribute from the GN to the Material, and use that attribute in the Shader Editor to change the images using the attribute as a factor for your Mix node.
This problem has appeared multiple times here in the forum, and by searching it normally you’ll find your answer before posting.
For example, this thread show some of the methods you might want to use. There are also other threads with similar discussions.