Get attribute data from other objects?

Any ideas on how to do this? I want to get vertex color off of a mesh that isn’t the object the material is applied to.

Specifically, what I’m thinking of should have a use with the new point-density procedural texture where you can reference other objects to generate the point cloud. Stuff like color shifting, or using a vertex paint grayscale to control a mix and drop the voxel radius where things get narrower on a mesh.

Afaik the only external reference you can have is location data from another object using object texture coordinate with a link input. I certainly wouldn’t mind more options in this area though.