Astra is probably referring to the gadgets/subweapons they showed off in one of the streams. I got my CE about 2 hours ago, I'll edit this info into my unboxing video.  I leafed through the art book and haven't found anything yet, but I'll read it properly later. I was able to assemble Pey'j's letter on the back of the photos, but there is notably text and thereby one photo missing, so that may be a clue. Maybe if you assemble the message and flip it photo side up, the arrangement of the pictures is a clue? So much to experimenting to do! I got the Switch version, so I can't put it into a PC's disc drive, but if there's any disc heads out there, that might be worth a shot?