I too am not seeing the option for Sandbox in the App Store menu on iOS 14.1. Did I miss a step setting up? So I need to install the app to test before I will see this option?
Statz
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution