Add the water, grape juice, pineapple chunks, and sugar to a medium saucepan and stir. Heat to a simmer, then simmer for 10 minutes.
After 10 minutes, strain out the pineapple pieces, squeezing them to get as much liquid from them as possible. Discard the pineapple and pour the liquid back into the saucepan.
Heat the pineapple liquid over low heat and whisk in the passionfruit powder and citric acid. Whisk until everything is dissolved.
Remove from heat, transfer to a large jar, and allow to cool completely before using.
Make the paradise drink: Add ½ cup Pineapple Passionfruit Refresher base and ½ cup sweetened coconut milk to a cocktail shaker or a large jar with a lid. Shake a few times until well combined.
Add ice to a tall glass, then pour the paradise drink over the ice. Garnish with freeze-dried pineapple pieces and drink up!
Notes
This makes 2 ½ cups of base, enough for 5 drinks. Store any leftover refresher base in the fridge for up to 1 week.