we could see that could see that test cards are available for adding Debit/Credit Cards to Apple Wallet.
https://developer.apple.com/apple-pay/sandbox-testing/
However, we are unable to find a way to add balance to Apple Cash in sandbox environment.
iOSDEV_24
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