Cut melon in half crosswise; remove seeds with a spoon. Using a melon baller, scoop out flesh and transfer melon balls to a bowl; reserve melon rinds to use as serving bowls. Add blueberries to the melon balls; toss to combine.
Stir together yogurt, maple syrup, lemon juice, and ginger in a small bowl.
Fill each melon rind with 1/2 cup of the yogurt mixture; top with 1/2 cup granola. Top with half of the melon mixture. Spoon 1/4 cup plain yogurt over each; garnish with more granola. To serve, spoon layered mixture into small serving bowls.