In a food processor, pulse 1/2 cup of the coconut until finely ground. Add the graham cracker crumbs, butter and 1/4 tsp. salt; pulse until combined. Press the mixture into a 9-inch pie pan. Bake for 10 minutes; let cool on a rack.
Meanwhile, remove 1/3 cup of the thick cream from the top of the coconut milk and reserve for the topping. Stir the remaining coconut milk until blended.
In a food processor, blend the cream cheese, 3/4 cup sugar, flour, vanilla and remaining 1/2 tsp. salt until smooth. Add 1/2 cup coconut milk and the eggs and egg yolk; pulse until blended. Pour into the crust; bake until the center is just set, about 35 minutes. let cool on a rack.
In a small bowl, whisk together the sour cream, reserved coconut cream and the remaining 2 tbsp. sugar. Pour the mixture over the pie; gently spread the topping over the filling. Let the pie cool completely, then refrigerate until set, about 3 hours. Sprinkle with the remaining coconut before serving.