Place the cut boneless chicken thighs into the inner liner of your Instant Pot or Pressure Cooker.
Add frozen soup blend (frozen veggies), water, and taco seasoning.
Close the lid and turn the knob to Sealing. Set at high pressure for 10 minutes.
At the end of the cooking cycle, allow the pot to rest undisturbed for 10 minutes. Then release all remaining pressure.
Stir in the evaporated milk (or milk substitute). Add cheese if using and stir.
Taste and add salt if needed before serving.
For lower-carb veggies that will do well in here, I'd recommend kabocha squash, cauliflower, and hardy greens such as kale or collard greens.
Switch out the evaporated milk with heavy cream or half and half.
Do not add the evaporated milk to the initial cooking. Milk separates under pressure and you will have a curdled mess. Add it after cooking as I have shown.
If you keep kosher or are dairy-free, you can use coconut milk instead.
Note that I have not asked for salt in the main recipe. This is because Taco seasonings vary is how much salt they contain.
Taste the soup after you've added everything including the milk, and then you can add salt if needed.