In a large bowl, whisk the brown rice flour, almond meal, oat flour, cornstarch, baking powder, and salt. In a medium bowl, whisk the buttermilk, eggs, butter, honey, and vanilla. Stir the wet ingredients into the dry ingredients until combined.
Coat a griddle or skillet with coconut oil and heat over medium heat until hot. Working in batches, ladle 1/4 cup of the batter per pancake onto the griddle or skillet, leaving a few inches of space between each to allow for spreading.
Cook until golden-brown on the bottom, 1 to 2 minutes (if adding blueberries, drop several on top of the pancake before turning). Flip and cook the pancakes until the other side is golden-brown, 1 to 2 minutes more.
Serve immediately, or transfer to a cooling rack set over a large baking sheet and keep warm in the oven. Apply more coconut oil between each batch as needed. Serve the pancakes with butter and pure maple syrup.
Regular brown rice flour or oat flour can be substituted for the sprouted flours.