Blender Geometry Nodes - How do I maintain Alpha from Instanced Mesh while Applying Source Material?

Question

I'm currently trying to achieve an effect that's similar to paint strokes on a source mesh. Basically I'd instance a basic plane across some geometry, and then have the plane (with an image of a brushstroke as an alpha) take on the color of the source object to appear like brushstrokes. If I had to think of an example, this would probably be a good one.

https://twitter.com/lettier/status/1546182746615283713?s=20&t=H-_AVfgKcGVbiURObMRbNw

I've gotten to the point where my instances take on the material and UV's of the source sphere however this reveals them as basic rectangular planes, and because the UV's do not match the original instanced plane I cannot use that alpha anymore. Is there a way for me to take the Instanced Plane's UV map before realizing this geoNode setup, and output it into the Source Sphere's Texture map as an Alpha? I would like to try and preserve the Plane's brushy alpha map but the color of the Sphere is the question.

Below is the current result without an Alpha map, but with the sphere's texture applied.

And here is the result with the Instanced Plane's Material and Alpha Map

Here is my current Shader for the Sphere's Material for reference, and also the Geometry Node Setup for the Sphere.

I'll also attach the blender file that I'm using at the moment in case it's needed!

https://drive.google.com/file/d/1jcoZ4T6eYxq8NfuQ2Bp6-cDFrQWCMq5n/view?usp=sharing

Answer 1

As long as you use Blender 3.2, you would basically only need to explicitly use the existing UV map of the planes in the shader:

The UV map of the sphere is used here for the color of the individual plnaes, and the UV map of the planes is used for the transparency.

By the way, you already get the normals from the node Distribute Points on Faces, so you don't need to get them additionally via Transfer Attributes.

_{(Blender 3.2)}