I'm not sure exactly what you're asking, but I think your way of thinking about Meraki is not totally right.
Config is a property of a network, not of a device. The device operates in the manner dictated by the network it is a part of, not by any configuration stored on it (You could consider an exception to this being when a device loses connectivity to the cloud it still operates, but the truth is that it must be part of a network before losing connectivity to do that. The config is till a property of the network)
If you truly want a "default" device then remove it from every network and do not add it to anther. This will cause the device to connect to the cloud, and effectively sit and wait for further instructions.