Preheat air fryer to 400° Fahrenheit.
Add 2 12-ounce bags frozen broccoli florets to large mixing bowl. Pour 1 tablespoon avocado oil over broccoli, then add 1 teaspoon garlic powder, 1 teaspoon kosher salt, and ½ teaspoon freshly cracked black pepper. Stir or toss to fully coat florets in oil and seasonings.
Transfer broccoli to air fryer basket and spread florets out evenly across basket. Return basket to preheated air fryer.
Air fry broccoli 10 minutes, then pause air fryer and remove basket. Shake basket gently to toss and flip florets, then return basket to air fryer.
Air fry broccoli 5 minutes, then check doneness. Continue air frying as needed, checking doneness every 60 seconds, until broccoli is browned and crispy.
Once broccoli is ready, remove basket from air fryer. Immediately sprinkle grated fresh parmesan and lemon zest onto broccoli florets if desired. Serve immediately.