Something to explore at a later date but it seems X3D and Collada are recommended when placing metadata (like exif) in a 3D file.

• For glTF (a 3D transmission format) posters seem to recommend an id that can link to an external file name or database.
• Obj can contain metadata but not structured metadata and https://digitalheritagerecording.wordpress.com/2015/03/12/photogrammetry-3d-object-metadata/ recommends X3D/VRML and Collada.
• NB Library of Congress has good online information about 3D formats especially for preservation.
• Above are just notes, there is probably material for a short survey paper on current popular formats and their capacity or potential for integrated metadata.