Turn on a multi-functional pressure cooker (such as Instant Pot®) and select Saute function. Cook pancetta for 1 minute. Add cubed pork loin, onion, and shallot. Saute until pork loin is starting to brown and onion is just starting to become clear, about 2 more minutes. Add olive oil if pork and onion bits are sticking to the pan.

Stir in potatoes and chiles and continue cooking for 5 minutes. Add corn, chicken stock, salt, and pepper. Cancel Saute mode.

Close and lock the lid. Select high pressure according to manufacturer's instructions; set timer for 35 minutes. Allow 10 to 15 minutes for pressure to build.

Release pressure carefully using the natural release method according to manufacturer's instructions, about 15 minutes. Unlock and remove the lid. Select Saute mode.

Remove lid, pour in half-and-half, and cook until heated through, 5 to 7 minutes. Correct seasoning with salt and pepper.