Preheat the oven to 350°F. Lightly grease a 9-inch pie dish. In a large bowl, combine the almond flour, coconut flour, and sea salt. Add the melted butter, egg, maple syrup, and vanilla. Stir until the mixture forms a soft, slightly crumbly dough.
Transfer the dough to the prepared pie dish. Use your fingers to evenly press it across the bottom and up the sides of the dish. Crimp or shape the top edge as desired.
Use a fork to gently prick the bottom of the crust several times.
Bake the crust for 8 to 10 minutes, or until it is just beginning to turn golden around the edges. Remove it from the oven and allow it to cool slightly while preparing the filling.
Roughly chop 1 1/2 cups of the pecans. Leave the remaining 1 cup of pecan halves whole for decorating the top of the pie. In a large mixing bowl, whisk the eggs until smooth. Add the maple syrup, coconut sugar, melted butter, vanilla, cinnamon, and sea salt. Whisk until thoroughly combined.
Stir the chopped pecans into the filling.
Pour the filling into the partially baked pie crust and spread the pecans evenly throughout the filling.
Arrange the remaining pecan halves over the top of the pie. Create concentric circles for a more decorative presentation or scatter them evenly across the surface for a rustic appearance.
Bake for 35 to 45 minutes, or until the edges are set and the center has a slight jiggle when the pie dish is gently moved.
Check the pie after approximately 25 minutes. If the crust edges or pecans are browning too quickly, loosely cover the pie with aluminum foil.
Remove the pie from the oven and place it on a wire cooling rack.
Allow the pie to cool completely for at least 3 hours before slicing. The filling will continue to set as it cools.
Serve at room temperature or chilled. Store leftover pie covered in the refrigerator.