1 small (6-pound) seedless watermelon
2 cups fresh coconut water (from 2 coconuts) or bottled coconut water 1 teaspoon finely grated lime zest plus 1/4 cup fresh lime juice, divided
2 tablespoons thinly sliced peeled fresh ginger
3 medium fresh green Thai chiles, stemmed and thinly sliced, divided
1 tablespoon turbinado sugar, divided
1 tablespoon extra-virgin olive oil
1/4 cup toasted flaked coconut
2 tablespoons crispy fried shallots (such as Maesri)
1 1/2 teaspoons finely chopped cilantro stems
1 teaspoon flaky sea salt