Preheat oven to 350℉. Prepare a 12-hole muffin pan with muffin liners, grease with cooking spray, and set aside.
In a medium-sized bowl, mix together rice flour, almond flour, sugar, baking powder, cinnamon (or substitute), and salt.
In a small bowl, mix together ground flaxseeds and water and set aside for 5 minutes.
In another medium bowl, peel and mash the banana with a fork. Add crushed pineapple, almond milk, oil, vanilla, and flax seed mixture, then stir until fully combined. Stir the mixture into the dry ingredients and stir to fully combine.
Fold chopped pecans into the batter.
Fill a quarter measuring cup with muffin batter, and fill each muffin pan hole until the batter is used up.
Bake for 25-30 minutes, until muffins are golden brown, and toothpick inserted into the center comes out clean.
Transfer the muffins to a cooling rack to cool completely. Store at room temperature in a tightly fitted container, or freeze for 2 months.