This is a simple demo using WebHID to switch Fn-key. Connect your keyboard (K380 by default), then click buttons below to set Fn-key as default. I collected some productId in case of your keyboard is not k380. These logi kbd should also supported. Click "Log Known Device Presets" to see if your device in the presets.
If none are your case, fill yours in the correct input textbox.
You may want to send your custom payload if you specify your productId.
Note that custom payload accepts an
HIDRAW send-style array:
the first element is outputDescriptor,
followed by the real payload being sent.
This is different from the
HIDDevice.sendReport.
tldr: concat the argument of HIDDevice.sendReport, then fill in the input.
Logs will display as follows.