Combine the coconut milk, soy milk, pumpkin pie spice, vanilla extract, salt and 4 of the bananas (broken in half) in a blender. Blend on high speed until smooth. Put the chia seeds in a medium mixing bowl or a large glass jar and pour the banana mixture on top. Stir well to combine, and put the mixture in the refrigerator for 4 hours or up to overnight to thicken. (Stir the mixture after 1 hour, to ensure no chia seeds settle to the bottom of the bowl or jar.)
Slice the remaining bananas. Spoon 3/4 cup chia pudding into each of 6 bowls, jars or parfait glasses, and top each serving with 1/4 cup yogurt, a sixth of the banana slices and 1/2 tablespoon coconut. Serve.
Serve with nondairy yogurt (coconut milk, soy milk or almond milk) instead of Greek yogurt for a dairy-free, vegan version.