You can obtain exclusive profile frames if you are one of the top players in the current league. Each league type will have its own exclusive profile frame aside from the beginner league.

Will this frame be available in Vanna's Showcase or Jewelry Shop?

No. This is only exclusive as a reward for winning World Tour League.

How about the event-themed World Tour Profile frames?

Event-themed World Tour Profile frames are limited time frames and can only be obtained from a limited-time World Tour League event.