Sauté onions with grapeseed oil in Instant Pot until soft. (Approx 5 min)
Add in all the other soup ingredients and stir.
Cancel saute and secure lid on Instant Pot. Make sure lid is sealed.
Cook on high pressure for 8 minutes. It'll take approx. 10-15 minutes for it to get up to pressure.
Once done cooking and countdown has finished, release pressure.
Take the chicken breasts out and shred with 2 forks, then return to pot and stir.
When serving, add toppings of your choice to the soup.