Turn Instant pot onto saute function. Add the vegetable oil when the display reads "hot". Add the beef, onion, garlic, carrot, Italian seasoning, salt, and pepper. Cook, stirring often and breaking up beef into large pieces, until the beef is no longer pink, about 5 minutes.
Turn off saute setting and 1/2 cup water. Stir, scraping up any brown bits on the bottom of the pot. Pour in the sauce and mix until combined.
Over the beef spread the broken spaghetti into 2 layers. Do NOT stir. Pour the remaining 1 1/2 cups water over pasta, again not stirring!
Lock the lid and set the valve to seal. Set function to "manual mode-high pressure" for 8 minutes. The instant pot will start on its own.
Switch the valve to the "venting" position to completely release steam before opening lid. If any sauce comes out in the jet of steam, close the vent and release the steam in bursts.
Carefully remove the lid (there will likely still be remaining steam). Mix the noodles with the sauce. Allow to sit for 4-5 minutes to thicken before serving.