Place water in small microwave-safe bowl. Sprinkle gelatin mixture over water; set aside.
Pierce potatoes with a fork and place on microwave-safe plate. Microwave on HIGH 6 minutes until tender. Let stand 5 minutes or until cool enough to handle. Remove skin and cut into chunks. Allow to cool completely, about 15 minutes.
Meanwhile, mix graham cracker crumbs, pistachios, coconut and 1/4 cup of the sugar in a large bowl. Stir in melted butter until well mixed. Press mixture firmly into bottom of parchment lined 9-inch springform pan. Set aside.
Microwave gelatin mixture on HIGH for 30 seconds. Stir until gelatin is completely dissolved.
Place cooled sweet potatoes and coconut milk in food processor; cover. Pulse until smooth. Add cream cheese, remaining 1/2 cup sugar, vanilla and gelatin mixture; puree until well-mixed and completely smooth, scraping down sides as necessary
Pour mixture evenly over prepared crust. Cover and refrigerate at least 4 hours or until set. Run small knife around sides of pan to loosen crust; remove sides of pan. Cut into slices to serve. Store leftover cheesecake in refrigerator.
Test Kitchen Tip: Ube, a bright purple sweet potato or yam, is a staple ingredient in Filipino cuisine. Ube are often used in sweet dishes and desserts and have a smooth texture and flavor similar to a typical sweet potato, but slightly sweeter with a bit of a nutty, vanilla taste.