Coconut oil, which is solid at room temperature, adds a mild sweetness; vegetable oil can also be used.
Preheat oven to 425 degrees. Line a standard 12-cup muffin tin with baking cups, or lightly brush with oil. In a medium bowl, whisk together flours, baking powder, and salt. In another bowl, whisk together granulated sugar, bananas, coconut oil, almond milk, and vanilla. Stir wet ingredients into dry until just combined. Fold in blueberries.
Divide batter evenly among muffin cups. Sprinkle tops with turbinado sugar. Bake until light golden and tops spring back when lightly touched, about 20 minutes. Let cool 5 minutes in tin, then transfer to a wire rack and let cool completely.