The Big Black Box of Boring as it is known is a small computer in the corner of the office with a small screen, some push buttons to navigate the menus and a serial lead. The chances of any users figuring out what’s going on inside the box is slim to none, but they are well informed on the state of Eastenders & Corrie.
RAK modules use the AT commands as we are plugging in to UART1. Arduino style modules either use a serial AT commmand-a-like or compile for each device, the latter being what makes it the Big Black Box of Boring as that takes slightly longer to run.
Alternatively batch run it on a developer computer as all you really need is the hex/bin file to be pushed through the command line programmer software.
Your original idea will break badly the day you have two customers installing at the same time or two installers from the same company or any other combination of having the same device credentials working at the same time, which may well end up with customers A creds being using on customer B’s device, but I think I’ve already said that.