Turn instant pot on sauté mode. When hot add the oil, onion and celery and sauté for 7-8 minutes stirring often.
Meanwhile, open the cans of clams and pass them through a sifter to separate from the juice. The four cans should yield about 2 cups of clam juice (see note 1)
Add clam juice, chicken broth, potatoes, bay leaves, garlic, pepper and thyme.
Close the instant pot and switch knob to sealing position. Cook on high pressure for 3 minutes. When done, allow for 10 minutes of natural pressure and then quick release remaining pressure.
While the pot is on cook the bacon on the stove top. Alternatively, you can use ready bacon, just be sure to chop it into bitesized pieces or you can also use bacon bits.
Open the instant pot. Turn on sauté mode once again. Take about 2 tbsp of the liquid into a small cup/ glass. Add in the cornstarch and whisk to dissolve.
Also remove about two cups of liquid and potatoes, add it to a blender cup and pulse for a few seconds. This will help thicken the sauce (see note 2)
Pour the blended potatoes back into the instant pot as well as the corn starch mix.
Discard bay leaves. Add in bacon, clams, and half and half. Stir to combine and let it simmer for about 10 minutes.
Serve with oyster crackers. You may also want to add a pinch of fresh ground pepper and parsley.