In a medium-sized bowl, add coconut milk, ½ cup of drained pineapple juice, and ½ cup crushed pineapple, whisk to combine.
Blend mixture for 30 seconds. You can skip this step if you like a chunkier pineapple texture.
Add 1 to 3 tablespoons of sweetener of your choice, depending on how you like your popsicles. Stir or blend for 15 seconds to combine. Transfer the coconut-pineapple mixture back to the medium-sized bowl.
Add ¼ cup chia seeds to the mixture. Stir until combined, and allow to sit at room temperature for 15 minutes. Stir to distribute the seeds (they should be thickening the mixture) and allow it to sit for another 15 minutes. Stir to combine one last time. The mixture should be like a thickened pudding.
Begin layering your popsicles as follows: Add 1 teaspoon of crushed pineapple, followed by 1 teaspoon chia mixture, then 1 teaspoon pineapple, 1 teaspoon chia mixture, 1 teaspoon pineapple, 2 teaspoons chia mixture, and 1 teaspoon pineapple as the last layer.
Gently tap each layer as you add them to allow the layers to settle evenly in the mold. You want the molds to be mostly full (about 95%), with just a small amount of room for expansion as it freezes. Insert the popsicle sticks into the molds, they should stand up by themselves.
Freeze for several hours until completely frozen.
To remove the popsicles from the molds, run hot water over the sides of each popsicle for about 15 to 30 seconds, or until the popsicles are just loosened.
Remove the popsicles from the mold and enjoy immediately, or tightly wrap them in plastic wrap and store in a resealable plastic bag in the freezer.