Use different textures for "mesh islands" in fbx with same material

Working on a custom shader graph. I have an object, consisting of different kinds of identicla mesh modules that have already been joined into one object fbx in blender. I want to build a shader that takes these individual modules in the mesh (sub-meshes) and assigns each one a different texture, randomly. how can i get access to information about the “mesh islands” within my parent fbx in the shader?

So my question: How to select between different textures in shader graph URP, depending on which mesh in the joined final fbx is concerende