Turn on a multi-functional pressure cooker (such as Instant Pot®) and select Saute function. Add olive oil. Add sausage and bacon to the hot oil and cook for 2 minutes, stirring constantly. Add onion and cook until tender, about 3 minutes longer. Add potato and saute 1 more minute. Add chicken broth and bring to a boil for 1 minute. Stirring, add corn kernels and corn cob rounds. Close and lock the lid. Choose high pressure and set timer for 6 minutes.
Release pressure using the natural-release method according to manufacturer's instructions, 10 to 40 minutes. Unlock and remove the lid.
Turn on the saute function and bring chowder to a boil. Add coconut milk and season with salt and pepper. Continue boiling until liquid has evaporated a bit and chowder has thickened, about 5 minutes. To increase thickness if desired, mix potato starch and water together in a bowl and add to the pot, stirring constantly until incorporated.