Cut butternut squash into 4 pieces and remove seeds. Pour water into the bottom of a multi-functional electric pressure cooker and place trivet inside. Place squash on trivet, close lid, and set seal valve. Select high pressure according to manufacturer's instructions; set timer for 10 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. Drain out the water and wipe the bottom of the pot dry. Remove squash skin and discard. Roughly chop any large pieces into smaller 1- to 2-inch chunks. Set aside.

Select the Saute function and heat olive oil. Saute onion and garlic for 1 to 2 minutes. Add pears, salt, and sage; cook for 1 to 2 minutes more. Turn pressure cooker off. Add the squash and chicken broth. Close lid and seal valve. Select high pressure; set timer for 5 minutes. Allow 10 to 15 minutes for pressure to build.