It was mentioned that Adventures have a bit different flavor here -- in Eldraine, they were adventures of the creature on the card, here they are YOUR adventures and the creature/object on the main card is something you have encountered/found on that adventure.
This technically counts as a real-life modern object turned into a Magic card, right?
Source: SpellTable
second its basically elvish piper/Quicksilver Amulet since you can cheat creatures
Technically according to the intros and fluff of monster manuals they're in-universe. Specifically Volo writes a lot of them.