Preheat oven to 350°F. Drain peaches; set aside 1/2 cup juice. Mix sugar, cornstarch, nutmeg and 1/8 tsp. salt in a saucepan. Gradually whisk in reserved 1/2 cup juice. Cook, stirring, until thickened, 4 minutes. Remove from heat. Fold in peaches and blueberries; transfer to an 8-inch square baking dish.
Combine flour, brown sugar and 1/4 tsp. salt in a small bowl. Stir in butter and almond extract until combined. Mix in almonds. Crumble mixture over fruit.
Bake until topping is lightly browned and filling bubbles, 25 to 30 minutes. Cool on a wire rack for 20 minutes. Serve with ice cream, if desired.