Geometry Nodes Per Instance Attributes Not Exported In GLTF file

[michaelharmonart]

Describe the bug
Although I'm not sure if this is yet implemented, it seems to me that the any attributes with the "per instance" scope should be exported in the gltf. This is especially useful for interchange with godot, where such data could be used in the import script to combine all instances into a multimesh3d with custom per instance data.

To Reproduce
Steps to reproduce the behavior:
Export a gltf of a scene with geometry nodes instances with a custom attribute set to "per instance"
open the gltf file in a text editor and notice that that attribute is not present.

Expected behavior
I would assume per instance attributes would be included in the node of the instance in the gltf file in the "extras" property or something similar

Screenshots

no extra data is present in the node

.blend file/ .gltf (mandatory)

shader_visualizer.zip
blend file in zip since github doesn't allow for .blend natively for some reason.

Version
linux
blender 4.3.2 and daily build (from a few days ago admittedly)