Blend blueberries – Add blueberries, 1–2 tbsp maple syrup, and lemon zest (if using) to a blender. Blend until smooth. Taste for sweetness.
Mix coconut layer – In a bowl, whisk coconut milk, the rest of the maple syrup, and vanilla until smooth.
Assemble popsicles – For layers, add blueberry puree to molds, freeze 15 minutes, then add coconut mixture. Repeat if desired. For a swirl, add both mixtures and stir lightly with a skewer.
Freeze – Insert sticks and freeze for at least 4–6 hours or overnight.
Unmold and enjoy – Run molds under warm water for a few seconds to release.