To cooled seed mixture, add oats, cocoa powder, chia seeds, maple syrup, avocado oil, and orange zest. Drain buckwheat and add to bowl along with other ingredients. Stir until well combined. Spread granola on prepared baking tray and bake, stirring every 10 minutes, for 30 minutes. Sprinkle cocoa nibs over granola on trays, give it a quick stir, and continue to bake until granola is golden brown and fragrant, about another 20 minutes. Let granola cool to room temperature on baking trays. As it cools, granola will crisp up. Once cooled, granola can be transferred to an airtight container and will keep in a cool, dry spot for up to 2 weeks. Serve as desired.