I'm... having the strong belief the Crown Tundra is a glorified Hoopa Rings/Ultra Space.Surprise!
There's Crown Tundra left overs
most of it (full thread) isnt too amazing but it seems like the Musketeers are part of an event for completing both parts of the DLC? That'd explain why they've also been weirdly absent from Legendary montages like Regigigas
e: Actually there's also Title Cards
It Came From The Ultra Beyond, eh?
EDIT: The Hoennian Zigzagoon that is given as a gift comes with Extreme Speed and three perfect IVs.