Wi-Fi QR

Type a network name to make the code.

Point the phone's camera at the code and tap the banner that pops up. You can also screenshot it and leave it with the client.

Network —

Password — Copy

Everything happens on this phone. The password isn't sent anywhere or saved, and the app works without signal once it has been opened once. It only makes a code from a password you already have; it can't find out an unknown one.