[Update: In what is easily one of the longest waits between My Nintendo merch announcements and a release date, Nintendo has released the Kirby's Dream Buffet keychain into the wild on December 22, 2022. You can find it here for 600 Platinum Points.]
In typical my Nintendo fashion it's only done in passing on a post about the greater Kirby franchise, but we do know the design (pictured here) and that it'll be celebrating Kirby's Dream Buffet. Typically, this means that the reward is roughly a week out. While there are no keychains currently for sale, they've ranged from 400 to 800 Platinum Points in the past.