I found something that kind of works. Here is the PG:
The createMaterial code was generated from this node material:
After reading @HiGreg’s post, I decided to look more into the node material editor and found this blog post:
Unfortunately, it appears to be limited to the name “color” and the orange mesh.color node, i.e:
mesh.registerInstancedBuffer("color", 4);
I couldn’t find a way to add, say, a white Color4 input, give it a custom name, and register it on the instance buffer. The code ran, but it appeared to have no effect. If that worked, then I think it would be pretty close to the Unreal functionality because then you could add as many attributes as you wanted and have them drive different things.