Warm the nut milk until a temperature of about 100° F is achieved. If it's too hot, it will kill the yeast. If it's too cold, the yeast won't activate. Note: the back of your yeast package should tell you the exact temperature to shoot for.
Combine the yeast, 1 tsp of the Truvia blend, and the nut milk until the yeast is mostly dissolved, then set aside.
Add the oat flour, pastry flour, and the rest of the Truvia blend to a mixing bowl, and combine thoroughly.
Add in the yeast mixture, the vanilla extract, and the lemon juice, then mix again. Finally, add in the coconut oil, and mix again.
Gently fold in the lemon zest.
Cover the dough with a towel and set aside for an hour to rise.
After the hour is up, place the dough on a sheet of parchment paper and roll it out to about 1/2" thick (you can go thicker for taller donuts).
Use large and small round cookie cutters to cut out the donut shapes.
Lightly grease your air fryer with oil and bake donuts for about 4 - 5 minutes at 350° F until golden brown.
Enjoy as is or make a light glaze by combining the 3 tsp Truvia blend with the 1 tsp nut milk and spread a generous layer on top of each donut.