The gallery base screen has been implemented! Since Cove's appearance can be different in Steps 2 and 3, and eventually 4, the gallery will show the version you most recently got in the game.
But you'll also be able to open the Cove Creator from the gallery to change his looks and have it reflected in the CGs right away.
(Step 3 has four CGs in the free base game, there will be two more if you get the DLC when it's done later on.)