Preheat oven to 375°.
Combine flaxmeal and warm water to for a slurry; set aside.
Combine almond flour, baking powder, and salt in a medium bowl.
Cut in shortening with a pastry cutter or two knives until mixture resembles coarse meal.
Mix together lime rind, 1/4 cup lime juice, maple syrup, and vanilla in a small bowl. Add mixture and flax slurry to dry ingredients, and stir until just combined.
Stir in 1/3 cup freeze-dried blueberries.
Divide mixture evenly among 8 greased donut pan wells.
Bake at 375° for 15 minutes or until golden. Allow to cool; carefully turn out donuts.
Place 1/4 cup freeze-dried blueberries in a small zip-top bag. Beat with a rolling pin to make a powder. Transfer blueberry powder to a medium bowl. Add powdered sugar and stir to combine. Add 1-2 tablespoons fresh lime juice to make a thick glaze.
Spoon glaze onto donuts. Top with sprinkles, if desired.