The Library of Congress made a scan of one of its copies of Star Wars at Disney’s request a couple months ago. I hadn’t heard about it either until the man in the forum linked in my comments (who I believe is trustworthy) made that statement. It isn’t the 4K restoration itself, but it would - from what I understand - be used as a comparison in any type of restoration of the OOT.

EDIT: I did actually personally contact the Library of Congress regarding the status of Star Wars, Empire, and Jedi and they did respond saying that a scan of Star Wars has been made. For what reason, they didn’t say, but I do believe the posts in the Steve Hoffman forums that it was made at Disney’s request