In large bowl, toss potatoes and thyme sprigs with oil, ½ tsp salt and ¼ tsp pepper. Add to air fryer and top with bacon. Air-fry at 400°F until bacon is crisp, 6 to 12 minutes. Transfer bacon to paper towel and let cool before breaking into pieces.
Shake potatoes and continue to air-fry 8 minutes. Add shallots to basket with potatoes, toss to combine and air-fry until vegetables are golden brown and tender, 8 to 12 minutes. more.
Meanwhile, in large bowl, whisk together vinegar, mustard and thyme leaves. Transfer cooked vegetables to bowl, adding any oils from bottom of basket, and toss to combine; fold in bacon.
