Turn on a multi-functional pressure cooker (such as Instant Pot®) and select Saute function. Add olive oil and onion. Cook until soft and translucent, about 4 minutes. Add garlic and cook until fragrant, about 1 minute. Cancel Saute function.
Add split peas, potatoes, carrots, liquid smoke, thyme, pepper flakes, bay leaf, salt, and pepper; stir to combine. Pour in vegetable broth and mix to combine. Close and lock the lid. Select high pressure according to manufacturer's instructions; set timer for 12 minutes. Allow 20 minutes for pressure to build.
Release pressure using the natural-release method according to manufacturer's instructions, about 10 minutes. Remove lid, stir, adjust salt and pepper to taste, and let sit for 5 minutes to thicken.