Preheat oven to 325°F. Line a baking sheet with parchment paper.
In a small saucepan over medium heat, combine peanut butter and maple syrup, stirring occasionally until smooth. Stir in oats.
Scatter oat mixture on baking sheet in small clusters and bake until lightly browned, 20-25 minutes. Set aside to cool completely.
In a medium saucepan combine blueberries, sugar, and lemon zest and juice. Bring to a simmer over medium heat and cook, stirring, until blueberries have burst, 8-10 minutes. Stir in cornstarch mixture and simmer just until thickened. Transfer to a bowl and cool completely.
To assemble parfaits, place a spoonful of the blueberry sauce in the bottom of each of 4 glasses or jars. Top with spoonfuls of yogurt, a sprinkle of peanut butter crunch, and a few cubes of pineapple and blackberries. Top with another layer of yogurt, a spoonful of blueberry sauce, a sprinkle of peanut butter crunch, and more pineapple and blackberries.