I have implemented Store Kit for my Swift UI App. I defined all products in app store connect (auto-renewables & non-renewables).
I tested everything in Xcode and it seems to run fine. However i want to test it in Sandbox to be able to check the server side dependencies.
After creating Sandbox users and logging in to those accounts on my physical device, i am still only able to do payments in Xcode ("[Environment: Xcode]").
I added the In-App Purchase Capability to my project in the Signing & Capability Targets and made sure the app runs in debug mode.
So according to the docs (https://developer.apple.com/documentation/storekit/in-app_purchase/testing_in-app_purchases_with_sandbox) everything seems to be set-up.