Preheat oven to 350 degrees F (175 degrees C). Line a baking sheet with parchment paper.
Zest lemons. Juice lemons into a measuring cup, adding water as needed, until 7 tablespoons liquid is reached. Combine lemon zest, lemon juice, coconut milk, chia seeds, and vanilla extract together in a bowl; set aside to thicken, about 10 minutes.
Dice chilled coconut oil on a work surface. Combine flour, sugar, cream of tartar, baking soda, ground ginger, and salt together in the bowl of a food processor; pulse to combine. Add coconut oil and pulse just until mixture resembles coarse crumbs. Add coconut milk mixture and pulse just until dough begins to clump and form a ball.
Turn dough out onto a lightly floured work surface; gently knead in pecans and hemp seeds to distribute. Separate dough into 2 equal portions; pat or roll each into a 1-inch thick round. Cut into 8 wedge-shaped pieces and place onto the prepared baking sheet.
Bake in preheated oven until tops spring back when lightly pressed, 25 to 30 minutes.