Sorry about the late response, I had to look into a few things to figure out how viable this was.
It would require some implementation to do this, so we can't currently prioritize it, but we would like to make the deluxe available on GoG in the future.
I didn't respond to this before, but I want to say thank you for at least wanting
to make the Deluxe stuff available here. There are other developers who are, sadly, very content with having the GOG version of their game be inferior to the Steam version in one way or another.