You’ve ordered a replacement board so it doesn’t really matter at this point but I don’t want anyone reading this later to be confused.
The M2 Nano that comes with the K40 has nothing to do with Arduino Nano. Different hardware and different firmware. GRBL cannot run on the M2 Nano.
It is proprietary.
I am sorry I confused the issue by bringing up Arduino but your original message was unclear. I read it as you had partial functionality in LightBurn which definitely can’t happen with the stock M2 Nano board.