They'll probably tie it to your icloud region and billing address. Sure, bring your European phone to the US, but you won't be able to access any paid Apple ser

They'll probably tie it to your icloud region and billing address. Sure, bring your European phone to the US, but you won't be able to access any paid Apple services because it only offers you the European subscriptions and they can't be bought with a US CC. Maybe even Apple Pay will not take your debit cards.