In a small bowl or cup, prepare your flax egg and set aside. Melt your coconut oil and set aside. Grate your lemon zest and set aside.
In a large bowl, combine almond flour, arrowroot starch, baking powder, and salt. Whisk to thoroughly combine. Add in lemon zest, whisk to evenly combine.
Add the flax egg, coconut oil, maple syrup, and vanilla extract to the dry ingredients. Use a rubber spatula to stir until most of the dough has come together and is moistened. There should only be a small amount of dry crumbs and pieces left.
Gently fold in blueberries, making sure to integrate remaining dry pieces. Use your hands to gently form dough into an imperfect disc. Place back in the bowl. If there are loose blueberries, press them into the top of the disc. Transfer bowl to refrigerator and chill for 30 minutes.
While the dough chills, preheat the oven to 400 degrees Fahrenheit. Line a baking sheet with parchment paper.
When the dough is chilled, place a piece of parchment paper on top of a cutting board. Transfer dough from bowl to cutting board. Dough may be slightly sticky, so you can lightly dampen your hands.
Form dough into a smooth and even disc about 6 ½ to 7 inches in diameter. Use a sharp knife and slice into eight triangles.
Transfer triangles to prepared baking sheet, arranging them in two even rows. Brush tops of scones with almond milk.
Bake for 16-19 minutes. Tops of scones should be golden brown and scones baked through. Check at the 16 minute mark to see if edges are getting too brown, tent with foil if necessary.
Allow blueberry scones to cool on pan. If using lemon glaze, stir together ingredients in a small bowl as scones cool. Once mostly cool, drizzle glaze and allow to set before serving.
Scones are best the day the are made. Store in an airtight container.