Whisk together the oil, vinegar, and ½ teaspoon each salt and pepper in a medium bowl. Add the shallot and toss to combine; set aside.
Top the pitas with the hummus, tomatoes, Feta, herbs, and half the shallot dressing, dividing evenly.
Toss the arugula with the remaining shallot dressing.
Serve the arugula alongside the pita pizzas.