Online Apple Gift Card purchases send the balance to your iPhone.
Online Apple Gift Card purchases send the balance to your iPhone.
Based on my experience, writing codes manually in Notepad won't work. You need the email with the scanned code. Adding those gift cards shouldn’t block purchases at the store—only limit online orders. Using them for physical purchases should be possible if you add them to your Apple account.
Just send the emails to the Apple Store and display the codes; they should process in about ten seconds. Why are you getting so caught up in gift cards?