1 (15 ounce) can cut sweet potatoes in syrup, drained (1/4 cup syrup reserved)
1 (15 ounce) can 100% pure pumpkin
1/2 cup canned coconut milk
1/3 cup light brown sugar
3 large or extra-large eggs, divided
2 tablespoons butter, melted
1/2 teaspoon ground cinnamon
1/4 teaspoon ground ginger
1/8 teaspoon ground allspice
1 prepared, refrigerated single-crust piecrust
1 cup sweetened flaked coconut
1/3 cup light corn syrup
1/4 teaspoon vanilla extract