Make the crust: Preheat the oven to 350 degrees F. Pulse the cookies and sugar in a food processor until finely ground. Add the melted butter; pulse until moistened. Press the mixture into the bottom and up the side of a 9-inch pie plate. Bake until set, about 15 minutes; transfer to a rack to cool.
Make the filling: Clean out the food processor. Pulse the sugar and herbs in the food processor until very fine. Whisk the eggs, 1/4 cup heavy cream, the cornstarch and coconut extract in a bowl until smooth; set aside. Combine the coconut milk, 1/4 cup heavy cream and all but 2 tablespoons of the herb sugar in a saucepan; cook over medium heat, stirring occasionally, until steaming, 5 minutes. Whisk 3/4 cup of the hot coconut milk mixture into the egg mixture, then pour the egg mixture into the saucepan. Cook, stirring constantly with a wooden spoon, until the mixture is thick like pudding, 3 to 5 minutes. Strain through a fine-mesh sieve into a bowl, using a rubber spatula to push the filling through; pour into the cooled crust. Cover the filling with plastic wrap, pressing it against the surface; refrigerate until set, at least 6 hours.
Remove the plastic wrap. Beat the remaining 1 cup heavy cream with the lime zest and 1 tablespoon herb sugar with a mixer until stiff peaks form. Spread over the pie; sprinkle with the remaining 1 tablespoon herb sugar and shredded coconut.