Yep. I included avocado from the beginning. And later grape tomatoes. They are my "treat" after protein and veg is done.
But even now, I limit them to 1oz each by weight on a scale. They are total slider foods and measure about 1/4c by volume.
At first I only did 1/2oz avocado. You def need to make it fit within your calorie window. I used it as my fat for the meal.