Bluetooth File Transfer on RAK8211

There's nothing specific built in, but it's trivial to do it by sending the JS code to write a file over the console interface.

Assuming you want to use the built-in Storage library (because that's easy and doesn't require an SD card - which you couldn't add on the RAK8211 anyway as you don't have enough free pins):

In your app, load the file, and convert it to base64 (btoa in JavaScript) and then send the following text over the bluetooth UART: "\x03\x10require('Storage').write('filename',atob('your_base64_encoded_data'))\n`

That'd be trivial to make as a Web Bluetooth page, and we had been considering providing that as a tool - but there is currently no existing app or standard that will just transfer a file over Bluetooth

and one of the arguments is a source path.

I don't understand I'm afraid - could you point me to the function/code you mean?