Preheat oven to 375°. Toast coconut on a rimmed baking sheet until golden brown, 3 to 7 minutes. Meanwhile, oil a 9-in. metal pie pan with cooking-oil spray; set aside. Put 2 tbsp. water in a small bowl, sprinkle gelatin on top, and set aside to soften. Melt 6 tbsp. butter.
Set aside 2 tbsp. toasted coconut. Pulse remaining coconut, the graham crackers, 2 tbsp. sugar, and the salt in a food processor until fine crumbs form. With motor running, drizzle in melted butter; whirl until well combined. Pour mixture into pie pan. Using a flat-bottomed measuring cup, press evenly over bottom and up sides.
Bake crust until golden brown, about 10 minutes. Let cool on a rack.
Meanwhile, in a medium heatproof bowl, whisk together remaining 1 cup sugar, 1 tsp. lime zest, the eggs, egg yolk, and gelatin mixture until well blended. Whisk in lime juice. Set bowl over a saucepan with 1 in. simmering water (bottom of bowl should not touch water) and cook, whisking constantly, until mixture very thickly coats a metal spoon and reaches 190° on an instant-read thermometer, 8 to 16 minutes; don't let it boil. If mixture reaches 190° but isn't very thick, reduce temperature and continue to cook, whisking, a few minutes more.
Remove bowl from heat and whisk in remaining 1/2 cup butter, 1 tbsp. at a time, until melted and well blended. Set bowl in a bowl of ice and water until cold, stirring occasionally, 10 to 20 minutes.
Spread lime curd in crust. Chill uncovered until filling no longer jiggles when gently shaken and a slender knife drawn through filling leaves a clean line, about 2 hours.
Whip cream in a bowl with a mixer until stiff. Spread over filling. Arrange berries on top, then scatter with remaining 2 tbsp. coconut and 1 tsp. lime zest.
Make ahead: Through step 6, chilled and loosely covered, up to 1 day.