Heat the oven to 350 degrees F. Mix the graham cracker crumbs, melted vegan butter, and 2 tablespoons granulated sugar until evenly moistened.
Press the crust firmly across the bottom and sides of a 9-inch pie plate. Bake for 9 minutes, then cool completely.
Whisk the coconut milk, oat milk, 3/4 cup granulated sugar, cornstarch, lemon zest, and salt together in a saucepan while still cold.
Cook the mixture over medium heat, whisking constantly, until it bubbles and becomes thick like pudding. Continue cooking for 1 minute to remove any starchy taste.
Remove the lemon cream from the heat and whisk in the lemon juice, vegan butter, and vanilla extract. Pour it into the cooled crust and smooth the surface.
Cool the pie at room temperature for 30 minutes, then cover and refrigerate for at least 6 hours until firm.
Spread the dairy-free whipped topping over the chilled pie and garnish with the remaining lemon zest before serving.
