The vSIM idea, which is similar to prepaid vouchers (except entering the voucher number):
You walk into the shop. Buy a vSIM.
Data is wirelessly transferred onto your phone. No need to input anything manually, no way to manipulate any information.
Additional network specific info might be transferred OTA upon initial subscription to the network.
PS: Not sure if it requires a special chip (NFC) or existing wireless interfaces can be used. Same for storing the info.