There are two ways to set the Wi-Fi credentials of an Argon: BLE and USB (serial).
BLE from a mobile app is the recommended way, and it’s how the Particle app does it. However there is no device setup library for Argon that extracts this process into something that would be easy to add to a mobile app like it is for the Photon. This will make it difficult to use an Argon in a product.