Hi y'all! I'm actually the artist behind the front cover's art (both our first one last year as well as this year's!) and I can answer some questions! I work for Geekify Inc and we have a contract with Neopets for making officially licensed products but unfortunately we don't have as close of a connection to the actual Neopets team enough to make canon stories like the usual Advent Calendars on the site! (I wish, though!)
The inside of the flap is just going to have the chocolates, shaped into molds I helped design based on some of the items from the site, like the snow paintbrush, a Snowbunny eating a negg, a Fir, a christmas negg, a christmas-painted meowclops, an angelpuss... there's a lot of really christmassy items I picked out and cleaned up for the chocolate company to make these chocolates into, but I'm not gonna spoil all of them--then there's no surprise!