Heat oil in inner steel pot of pressure cooker set to Sauté on High. Sauté onion and garlic in hot oil until translucent, 2 to 3 minutes. Add chicken to onions and season with chili powder, salt, and pepper. Sauté until chicken is golden brown on all sides, 2 to 3 minutes per side. Stir diced tomatoes, chipotle peppers with adobo sauce, and water into chicken. Lock pressure cooker lid in place and set steam vent handle to Sealing. Select Pressure Cook (Manual) and cook on High Pressure for 10 minutes. When cooking cycle is complete, move steam vent handle to Venting to quick-release pressure. Transfer chicken to a deep plate or bowl with a slotted spoon. Use 2 forks to shred chicken. Add 1 cup cooking liquid to shredded chicken and stir. Top warm tortillas with shredded chicken and garnish with shredded cheese, fresh cilantro, and a squeeze of lime.