Pusblishing an app to App Store and Play Store that talks to Internal Web Service

Firstly, excuse the question if it sounds ignorant or even clueless. We have an app that talks to a Web Service running in an Intranet. We wanted to publish the app in the App Store and Play Store (instead doing Enterprise publishing). This allows our users of our software to download the app from App Store and/or Play Store. For Apple and Google to review our app we have to provide their reviewers access to the Web Service which means creating a server that sits outside our firewall or Internet accessible for them to test/run the application. Since they will have no way of testing the app without the Web Service then we are assuming that there is no way around this. Is this correct? Thanks!