You have to deploy and publish one app per environment. So in our case we have three app deployed to IOS and Android. By using (in case of IOS) testflight you are able to deploy the test apps to you test group and the one in production to the public app store. In my opinion you always have to do it this way as you environment are separated servers so each app has a different endpoint. For IOS see: https://developer.apple.com/documentation/xcode/distributing-your-app-for-beta-testing-and-releases For Google: https://developer.android.com/guide/app-bundle/test
Thank you for your help Christian.