Use a virtual gift card of Apple store to recharge the Apple Pay?

Hi. When you redeem App Store & iTunes gift cards you add credit to your Apple ID balance. You can use that credit to make purchases in the App Store, iTunes Store, Apple TV app, or Apple Books. Or you can use the credit to upgrade your iCloud storage or pay for subscriptions like Apple Music, Apple Arcade, Apple TV+, Apple TV channels, or Apple News+.

But you can't add money from a gift card, even it is already in your Apple Wallet.

Hope that helps.

-- JDee