Pour off ¼ cup juice from 1 (20-ounce) can unsweetened pineapple tidbits and place in a large bowl.
Whisk in ¾ cup mayonnaise, 1 tablespoon apple cider vinegar, 1 teaspoon kosher salt, ½ teaspoon black pepper, and ½ teaspoon granulated sugar until combined.
Drain off the remaining juice from the pineapple and reserve for another use.
Add the pineapple, 2 (12-ounce) bags coleslaw mix, 4 thinly sliced medium scallions, and ⅓ cup coarsely chopped fresh cilantro, and toss to combine.
Serve immediately, or cover and refrigerate for up to 3 hours before serving. Toss again before serving.
