Heat olive oil in a Dutch oven over medium-high heat until shimmering, about 30 seconds. Add garlic, onions, and bell peppers. Sauté for 3-5 minutes, stirring frequently, until onions are translucent and peppers are softened.
Add diced jalapeño, chicken broth, fire-roasted tomatoes with juices, and chicken breasts to the pot. Sprinkle in cumin, chili powder, salt, and pepper. Stir gently to combine.
Bring to a rolling boil over high heat, then reduce to medium-low. Cover partially and simmer for 30 minutes until chicken is cooked through.
Remove chicken breasts with tongs and place on a cutting board. Let cool for 1 minute, then shred using two forks. Return shredded chicken to the pot.
Stir shredded chicken into the soup and simmer for 5 more minutes to allow flavors to meld.
Ladle soup into bowls and top with shredded Monterey Jack cheese, avocado slices, sour cream, fresh cilantro, keto tortilla chips, and lime wedges. Serve immediately.