I managed to get 10 out of 13 endings and I'm listing the ones I got!
Ending 1: Jammie Dodger - Use the credit card to purchase cookies.
Ending 2: Digestive - Stack the books and climb on them to reach the cookie jar.
Ending 3: JaffaCake - Use the 'Be one with' Concept on the cookie jar.
Ending 4: Chocolate Chip - This is the one where you straight-up summon a demon.
Ending 5: Oreo - Blackmail Wendy
Ending 6: Rice Cracker - Edit the magazine, then sweeten the wine and use it on Wendy. Oncethis is done give her the magazine.
Ending 7: ??? - ???
Ending 8: ??? - ???
Ending 9: Kitchen Sink Cookie - yeet an item at something that you want to break (or if you got the lighter, torch something), then keep destroying the area.
Ending 10: Fortune Cookie - Hack the bookcase, then use the secret passageway to reach the magical wish-granting cookie tree.
Ending 11: Website Cookie - Hack Wendy.
Ending 12: ??? - ???
Ending 13: Mega Cookie - Hack the TV to reach the cookie stock channel, then use the 'Stock tips' concept on the computer, then check all the boxes and set preferences.