At this point I don't expect it will still happen.

We've seen no further updates about this. Not entirely sure how difficult it is to add a DLC package to simply generate and deliver the items, but one could reason it's hard enough no one @ GOG or Obsidian want to do it for the GOG users.

https://forums.obsidian.net/topic/103909-patch-notes-for-1220033/

Well now they added the items after all. :) Yay! :P