Preheat oven to 350℉.
In a food processor, pulse crust ingredients until combined and granola is ground to crumbs. Lightly coat a 9-inch pie dish with cooking spray and press crust into bottom of dish and up the sides. Bake for 10 minutes. Cool completely.
In a small saucepan over medium-high heat, stir together raspberries, 1 tablespoon agave syrup, 1 tablespoon water, juice of half the lemon, and ½ teaspoon cornstarch.
In another small saucepan over medium heat, stir together blueberries, 1 tablespoon agave syrup, 1 tablespoon water, juice of the other half of the lemon, and the other ½ teaspoon of cornstarch. Simmer both saucepans of berries until berries have broken down and sauce has thickened, stirring occasionally with a whisk, about 10 minutes. Cool and pour each sauce separately through a fine-mesh sieve into small separate bowls. Let sauces cool completely.
Pour sauces into resealable sandwich bags. Snip a tiny amount off one of the corners of the bags. Alternating bags, pipe circles about 2 inches apart over the pie, starting in the center and working outward. Drag a toothpick from the center of pie outward to the crust so that the berry sauces are pulled upward. Drag toothpick back in the other direction (from crust to center) about 2 inches away from the first line. Continue around the pie. Freeze uncovered at least 3 hours. Cover with plastic wrap until ready to serve. Serve with additional berries and any remaining sauces.