I don't know how to use our app on Steam Deck,so thesolution I can provide isnt direct to your issue. My first suggestion is to not use steam deck to play our AVN. Otherwise, the persistent save file should be in the saves folder on Book 2, then just press start on Book 2. If that doesn't work then you can hop on our discord server, you can get a save file at the beginning of Book 2 that follows the canon route and you can load the game from there.