Preheat oven to 425F and line a baking sheet with parchment paper.
Whisk the pumpkin puree, coconut sugar, milk, and vanilla in a small bowl. Set aside.
In a medium-large bowl, combine the flours, baking powder, sea salt, and pumpkin pie spice. Use a knife to roughly chop the butter into small cubes into the dry ingredients and mix.
Slowly pour the wet ingredients into the dry and mix until just combined. If it sticks to your fingers at a light touch, add more oat flour by the tablespoon until the dough dries out just a bit.
Sprinkle a small handful of oat flour over the parchment paper. Scoop the dough onto the paper, lightly roll it in the oat flour, and form into a circle about 1 1/2-2" tall (it shouldn't be flat). Cut into 6 triangles and distribute evenly over the baking sheet
Bake for 15-17 minutes, or until golden brown on top and firm to the gentle touch. Remove from the oven and cool completely.
In a small bowl, whisk together the Greek yogurt and maple syrup. Once the scones have cooled, scoop a dollop of frosting onto each scone and spread over the top. Finish with a sprinkle of cinnamon and serve immediately. Store leftovers in an airtight container in the fridge for 1-2 weeks.