Press Saute on the Instant Pot and when the display says Hot, add the bacon if using. Cook until almost crisp and then add the onion, carrot, celery and red pepper. (If you prefer to omit the bacon, use 2 Tbsp butter.) Saute for 2 or 3 minutes and then press Cancel and add the broth.
Deglaze the pot: thoroughly scrape all the browned bits up off the bottom of the pot into the liquid. Add the potatoes, thyme, salt, pepper and hot sauce and close the pot.
Make sure the valve is set to Sealing. Push Pressure Cook (or Manual) and use the + and - buttons to get to 6 minutes.
When it beeps that it's done, flip the valve to Venting for a quick release and when the pin drops, press Cancel and open the pot.
Press Saute and add the corn and sugar. Bring it to a boil and simmer for a minute or two. Use a potato masher to break up some of the potatoes. If you like a thicker chowder, stir together the cornstarch and water and add about half of it, stirring constantly. Add more if you like it even thicker.
If you are adding crab, stir it in now. Let it cook for just a minute to heat the crab and then press Cancel .
Add as much cream as you like - anywhere from 1/4 to 1 full cup. Taste and add salt and pepper if needed. Serve with a garnish of bacon bits or red peppers. Or, what the heck, just dig in.
Notes
Pressure Cook and Manual buttons are interchangeable.