Does Apple currently allow one to test obtaining new IAP content through StoreKit if that IAP is meant for the next unreleased version of the app?
From what I can tell, iTunes Connect explicitly warns you that new IAP items that are meant for future versions of the app will be always rejected, and that you need to submit those for review in parallel to submitting the next app version.
Is there perhaps a way to have those non-reviewed items be visible to StoreKit in the sandbox environment?
To answer my own question, you are in fact able to see not-yet-reviewed IAPs from StoreKit, meaning that you can test those items as soon as they’re declared in iTunes Connect.