Does the S6 Pro need the flash done, as outlined for the S9?
In the title you are talking about the S6 Pro, in the text you write S9 Pro. There is no S9 Pro.
But if you are asking if both models can be flashed with the same firmware, then yes. Both include (nearly) the same mainboard. You can find the full guide here: Firmware Update & Settings - Diode Laser Wiki
@misken You are correct, I meant the S6 Pro. Thank you for the info