Place ham on a trivet and set it inside a multi-functional pressure cooker (such as Instant Pot®). Pour crushed pineapple over ham. Sprinkle brown sugar and drizzle maple syrup on top. Secure the lid with vent closed.
Select high pressure according to manufacturer's instructions; set timer for 35 minutes. Allow 10 to 15 minutes for pressure to build.
Release pressure using the natural-release method according to manufacturer's instructions, 10 to 40 minutes. Remove ham and trivet. Cut ham into slices and place on a plate.
Select Saute setting on the pressure cooker. Mix cornstarch with water until smooth. Stir mixture into the pot, bring to a boil, and stir until thickened. Pour sauce over the ham.