I Have implemented IAP in my swift project. It is working fine. it will work with live app or not.
Secondly url of Live app and BetaTester url is same or not?
YES. if your testflight app working then your Live App is also worked fine.
in BetaTester App testing is show you Environment Sandbox when you are Purchasing in IAP. when your App is Live then the Environment is autometically changed to live.