Break spaghetti noodles in half and place in a multi-functional pressure cooker (such as Instant Pot(R)). Add water, garlic, olive oil, and salt. Close and lock the lid. Select high pressure according to manufacturer's instructions; set timer for 6 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.
Combine shrimp, mayonnaise, chili sauce, lime juice, and Sriracha(R) in a bowl; mix until well coated. Pour into the pot and select Saute function. Add chopped green onions and cook until shrimp are pink and green onions are tender, about 7 minutes.