Spread pineapple in an even layer on a baking sheet lined with parchment paper. Freeze at least 8 hours or up to overnight. Place frozen pineapple, coconut cream, agave, and salt in a food processor; pulse until finely chopped, about 40 times. Process until smooth and airy, 3 to 4 minutes, stopping to scrape down sides of bowl as needed. Serve soft, or transfer to an airtight container, and freeze until just firm, about 1 hour. Garnish with flaked coconut.