LEDs can still work ! It is just that the UI (User Interface) needs to work DIFFERENTLY than a WIRED keyboard. For example:
# Pressing the caps lock key could make a led blink twice for “On”, Once for “Off”, a second press within 2 seconds would CHANGE the status.
# A DEDICATED key or small button could momentarily light up a led Green for “On”, red for “Off”
# I am sure that Logitech can think up a usable scheme ????
Maybe we can all contribute an answer!!!!!!!