Preheat oven to 350 degrees. Lightly grease a 9-inch pie plate (not deep dish) with coconut oil and set aside.
Place nuts in the bowl of a food processor. Pulse until coarsely chopped. Add oats and 1⁄4 teaspoon salt. Pulse until the mixture is finely chopped. Do not overprocess; mixture should have coarse texture and should not be ground. Add 3 tablespoons honey and 3 tablespoons coconut oil and pulse until incorporated. Mixture will be crumbly, but should hold together if pressed in your hand. Transfer to prepared pie plate and using hands or the bottom of a measuring cup, press into an even layer and up the sides.
Bake 20-25 minutes, until crust is golden, tenting the edges of the crust with foil if necessary to prevent over-browning. Remove from oven and let cool completely.
Meanwhile, place sweet potato on a parchment-lined baking sheet. Transfer to oven and roast until cooked through and very tender, about 1 hour 15 minutes. This can be done at the same time as the crust, or if done separately, sweet potato can roast at 400 degrees for about 1 hour.
Transfer sweet potatoes to the bowl of a food processor, along with coconut milk, remaining 1 tablespoon honey, and remaining 2 tablespoons coconut oil. Process until smooth, scraping down the sides of the bowl as necessary, and transfer mixture to cooled nut crust. Spread into an even layer, cover lightly with plastic wrap, and place in refrigerator until chilled and firm, about 1-2 hours.
To serve, top pie with coconut shaving and chopped pistachios. Cut into slices and serve.