Here's the Orioles' bag policy: https://www.mlb.com/orioles/ballpark/information/securitykinda related but more a curiosity.
Camden Yards in Baltimore currently is the only stadium I know of that allows fans to bring outside food and drink inside the stadium as long as it’s unopened. Are there any others? Not talking about ‘sneaking things through’, talking walk straight up with sub, bag of unopened peanuts and a Diet Coke and it’s ‘Have a great time’