Map Logitech K780’s hardware `fn` key (unrecognized) to `keyboard_fn` key_code?

[CLBarajas]

macOS version: 12.4 Karabiner version: 14.5.0 Your Mac hardware: MacBook Air (M1, 2020)

Your keyboard hardware: Logitech K780

    {
        "device_id": 4294996687,
        "is_karabiner_virtual_hid_device": false,
        "is_keyboard": true,
        "is_pointing_device": false,
        "location_id": 1364155725,
        "manufacturer": "Logitech",
        "product": "Keyboard K780",
        "product_id": 45883,
        "serial_number": "31C9BF3452EDCCB5",
        "transport": "Bluetooth Low Energy",
        "vendor_id": 1133
    }

The fn key on the keyboard is not recognized by Karabiner-Elements on its own as a key. Here's what I've found in the EventViewer:

• fn down

value:52             HID usage: 65347,-1 
value:223338302207   HID usage: 65347,-1 

• fn up

value:0              HID usage: 65347,-1 
value:2815           HID usage: 65347,-1 

I'd like to be able to use it to trigger the keyboard_fn key code, but I'm not sure how to do that without actually getting the key values recognized normally in Karabiner-Elements. Any suggestions?