Turn on a multi-functional pressure cooker (such as Instant Pot®) and select Saute function. Add bacon and cook until browned and crispy but not burned, about 6 minutes. Transfer bacon to a baking sheet lined with paper towels. Allow grease to drain.

Pour off some liquid from the beans, clearing at least 1 inch from the top of the can, but leaving some liquid. Add beans and remaining liquid, ketchup, brown sugar, and mustard to the Instant Pot®. Mix in bacon. Close and lock the lid. Select high pressure according to manufacturer's instructions; set timer for 3 minutes. Allow 10 to 15 minutes for pressure to build.

Release pressure carefully using the quick-release method according to manufacturer's instructions, about 5 minutes. Unlock and remove the lid.