Preheat the oven to 425F. In a bowl, combine thinly sliced red onion with grated garlic, lime zest, lime juice, apple cider vinegar, maple syrup (if using), minced cilantro, and a pinch of kosher salt.
Pat dry the drained chickpeas and transfer them to a baking tray drizzled with avocado oil and seasoned with salt. Toss to coat evenly and arrange in a single layer. Bake for about 20 minutes until crispy.
In another baking tray, combine cauliflower florets with garlic powder, ground coriander, onion powder, dry thyme, avocado oil, and salt. Toss to coat and spread cut-side down before roasting in the oven alongside chickpeas.
Blend chipotle peppers, plant-based yogurt, vegan mayo (if using), lime juice and zest, and grated garlic until smooth. Adjust thickness with water if necessary.
Mix roasted chickpeas and cauliflower together in one tray, drizzle with chipotle sauce, and toss gently until well combined.
Warm pita according to package instructions, spread chipotle sauce on top, add fresh lettuce, chickpea-cauliflower mixture, and pickled onions if desired before wrapping tightly.