On both Android and iOS unreleased apps can be tested using Lookback's Participate app, as both versions record the entire screen:

Android Participate app

iOS Participate app 

So it doesn't matter how the app is tested, as long as the user can access the prototype or testflight environment etc then the Participate app will record the users entire device.

Here are some demo videos of how to conduct remote moderated
(Live) and remote unmoderated (Self-test) sessions.

Did this answer your question?