Hi, sadly that goes against this statement:
If your app needs a native feature (example: BLE), well, then you might need an app.
Unless you are using Muons. There you can use a function call via cellular to configure Wi-Fi credentials.
If most of your customers are on Android, you could use the combination of the ble-wifi-setup-manager library and this Android app. Or that library and a chrome-only web app.