Turn ON Instant Pot to SAUTE mode (high). When it displays "HOT" add oil.
Add onion, garlic, celery, carrots. Saute for 2-3 mins or until onions are translucent.
Add the chicken, diced tomatoes, tomato sauce, chicken stock, thyme, salt and pepper.
Set Instant Pot to MANUAL / PRESSURE COOK mode (High) for 10 mins. Let pressure release naturally, around 10 mins.
Open the Instant Pot remove the chicken breast out. With the help of a fork, shred the chicken.
Turn ON Instant Pot on SAUTE mode (High). Add the shredded chicken back into the soup, add cabbage, bring the soup to a boil, adjust the seasoning. Cook for 3-5 mins or until cabbage is tender and cooked to a desired texture. Serve hot. Enjoy!