Step 1: Prepare the pineapple. Cut off the top and bottom of the pineapple. Carefully slice off the skin. Using a pineapple corer or a small cookie cutter, remove the tough core from each slice. Slice the pineapple into 1/4-inch thick rings.
Step 2: Make the simple syrup. In a large pot, combine granulated sugar, water, and light corn syrup. Bring to a simmer over medium heat, stirring until the sugar is fully dissolved.
Step 3: Candy the pineapple. Reduce heat to low. Add pineapple slices to the syrup in a single layer (you may need to do this in batches). Simmer for 10-15 minutes, flipping halfway, until the pineapple appears slightly translucent. Remove pineapple with tongs and place on a wire rack set over a baking sheet to drain excess syrup.
Step 4: Dehydrate the pineapple. Arrange the pineapple rings in a single layer on dehydrator trays or oven racks (if using an oven, set to the lowest temperature, around 150-175°F / 65-80°C). Dehydrate for 2-3 hours, or until the pineapple is chewy and slightly tacky but no longer wet. Flip occasionally for even drying. If using an oven, prop the door open slightly with a wooden spoon to allow moisture to escape.
Step 5: Prepare the Skittles. While the pineapple is dehydrating, crush the Skittles. You can do this by pulsing them in a food processor or placing them in a sturdy Ziploc bag and crushing them with a rolling pin or meat mallet until they form a fine powder with some small candy bits.
Step 6: Coat with Skittles. Once the candied pineapple rings are cooled and dried, lightly moisten one side of each ring by dabbing it with a tiny bit of water or the remaining simple syrup (if still sticky enough, you might not need this). Immediately press the moistened side into the crushed Skittles, coating thoroughly. Gently shake off any excess.
Step 7: Final drying (optional). If the Skittles feel a bit sticky, you can return the coated rings to the dehydrator or oven for another 30-60 minutes on low heat to set the candy coating. Allow to cool completely before storing.