As guessed, most cosmetic items are encrypted.
New cosmetic items are basically limited to a few skins. Of course, more items will be added as time goes by, while at this point it looks rather average. The most interesting seem to be the superstyles:
New skins
There are three new skins. Two are from the concepts that won the skin contest. It is unofficially known that a total of 7 things are coded – probably skins for Fortnitemares, or Halloween.
There are some novelties, but cosmetic items are definitely not the strongest point of this update.