Preheat oven to 350°F (175°C) and lightly grease a donut pan. In one bowl, whisk almond flour, coconut flour, pumpkin pie spice, baking powder, and a pinch of salt.
In another, mix pumpkin puree, keto sweetener, eggs, melted butter, and vanilla until smooth.
Fold dry ingredients into wet until just combined—the batter should be thick but spoonable. If too dry, add a little more pumpkin; if too wet, sprinkle in coconut flour.
Spoon batter into the donut pan, filling each mold about ¾ full. Bake 15–18 minutes, until golden and a toothpick comes out clean.
Let cool 5 minutes in the pan, then transfer to a rack.
For the glaze, whisk powdered sweetener, heavy cream, and vanilla until smooth. Dip donut tops and let set before serving.