I bought an iTunes gift card to give to someone in Germany

See this Apple article:  If you can't redeem your Apple Gift Card or App Store & iTunes Gift Card

If you can't redeem your Apple Gift Card or App Store & iTunes Gift Card - Apple Support

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Card is not valid

Card has already been redeemed

Card is not activated

Code is unreadable

Code must be redeemed in a different country or region

Contact Apple Support -> Contact Apple Support.

See also -> About Gift Card Scams -> About Gift Card Scams - Official Apple Support

They'll get told that it needs to be redeemed in the USA storefront.

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