Prepare the glass rims by mixing lime zest, coconut flakes, and salt on a small plate. Run a lime wedge around the rim of each glass, then dip into the mixture to coat. Set aside to dry slightly.
Blend the lychees in a blender or food processor until smooth. If using canned lychees, add the reserved syrup for additional sweetness and flavor.
Combine the lychee puree, coconut milk, lime juice, and simple syrup in a cocktail shaker. Shake vigorously for about 15 seconds to fully integrate the coconut milk with other ingredients.
Add ice to the shaker and shake again for another 20-30 seconds until the mixture is well-chilled and slightly frothy.
Fill the prepared glasses with fresh ice and strain the mocktail mixture over the ice.
Garnish each glass with a lime wheel and a whole lychee on a cocktail pick. For extra flair, sprinkle a few coconut flakes on top.
Serve immediately while cold and frothy for the best taste experience and texture.