... but they both have Wi-Fi capabilities & your app is already used to communicate with the device. The phone reads & translates the QR code anyway. I don't think it much of a challenge to output it to a configuration file &/or saves it in the GL.iNet app's sqlite database (assuming it has one) just like any other saved profile. The user would scan the QR code via the app, connect to the device, chooses the newly saved profile, enters their device creds (if not already saved on the phone to 'auto login') to push over the profile (like using dropbearor other scp client/curl)
I don't do mobile app development but I can tell you I already have parts of OWRT, including on GL.iNet firmware, execute similar tasks like the dynamically re-configuring the firewall, other aspects to push & pull data (via curl or rsync) to/from hosts base on various changing states:
There's already a camera available. I don't think a function to output & P2P sync a JSON/XML/TOML file from a mobile app to a Linux-based device is beyond the skills of GL.iNet developers. It's not beyond mine.