I am interested in the answer to this question too. Please respond. In fact, widgets are part of an app and can be its high value. If developers should use the new WidgetKit, let them show the effect to the potential user in the store. Users will also appreciate getting know what is included to the app, same as e.g. Watch version. All in all, I think that screenshots with widgets show the app in use as states in official guidelines. I have already had passed reviews with widget screenshots and one rejected because of that.