Gift cards with cryptocurrencies would be awesome. As I understand that right,:customers would get whole wallets with private keys. But there is a problem like on physical Bitcoin. You need a trustable centralized service, which garants the correct amount and that it will not be moved out the wallet, except from buyer. I don't know, how ATM work. Probably similar. Or is there another solution to asure, that buyers will get their cryptocurrencies? If they found a secure way it could grow fast and find the way to several shops.