Bring coconut milk, cardamom, cinnamon sticks, ginger, pepper, and 1½ tsp. turmeric to a simmer in a large saucepan over medium heat. Remove from heat, cover, and let infuse 20 minutes.
Combine egg yolks, cornstarch, salt, and ½ cup maple syrup in a large bowl. Whisk until very smooth. Stir together remaining ½ tsp. turmeric and 1 tsp. maple syrup in a small bowl; set aside.
Whisking constantly, strain infused coconut milk through a fine-mesh sieve into egg yolk mixture; discard solids. Return custard to saucepan. Heat over medium and cook, whisking constantly, until custard is thick and bubbling, 3–4 minutes.
Remove from heat and, working quickly, add coconut oil and stir until smooth. Immediately pour custard into crust, filling as high as the crust allows without spilling over. Drizzle maple-turmeric syrup over and swirl decoratively by dragging the handle of a small spoon or chopstick through filling several times
Press a large piece of plastic wrap onto surface of pie and cool until set, at least 2 hours. Top with coconut flake mixture before serving.
Do Ahead: Pie can be made 3 days ahead. Keep chilled.