Set a 6-quart Instant Pot to saute; add olive oil.
Sprinkle pork loin evenly with salt and pepper.
When oil is hot, add pork to Instant Pot.
Cook until browned on both sides, about 4 minutes per side. Remove pork; set aside.
Add onion and garlic to Instant Pot; saute 3 minutes, stirring occasionally.
Add wine to Instant Pot; stir to release browned bits.
Press Cancel to reset Instant Pot. Stir in tomatoes, olives, zest, and thyme or oregano. Return pork to Instant Pot.
Place top on Instant Pot; twist to seal and lock. Turn Steam Release Valve to “sealing.”
Set Instant Pot to cook at High Pressure for 16 minutes.
After cooking is complete, let pressure release naturally (approximately 10 minutes). After
that, manually release the pressure by turning the Steam Release Valve to “venting.”
Remove pork from Instant Pot; let rest 5 minutes.
Slice pork as desired, and top with tomato-olive mixture.