1.) That's clearly Brainiac at the top of the Blu-Ray spine. Perhaps the movie's big bad for the climax or part of an end credit tease for a follow-up movie?
2.) I might be crazy but that looks like Wonder Woman's bracelet, suggesting that the top of the Blu-Ray spines might create an over-arching image in the future AND that we could be looking at a brand new in-continuity set of movies. A new WW movie after
Batman: Soul of the Dragon? We'll just have to wait and see.
Here's a link to
Amazon UK where the image can be magnified.