Turn on a multi-functional pressure cooker (such as Instant Pot®). Add chicken stock, tomatoes, onions and garlic to the pot. Place chicken breasts on top and sprinkle with chilli powder, cumin, paprika, salt and pepper. Add sweetcorn and cabbage on top; do not stir. Close and lock the lid. Select high pressure according to manufacturer's instructions; set timer for 8 minutes. Allow 10 to 15 minutes for pressure to build.
Release pressure carefully using the quick-release method according to manufacturer's instructions, about 5 minutes. Unlock and remove lid. Remove chicken from pot and place in a plate; shred with 2 forks. Put chicken back into the pot with cooked quinoa, lemon juice and tortilla chips. Sprinkle with chopped coriander.