Go ahead... put gear oil in your M6 and within a few weeks/months one trackday, you will be complaining that your eLSD is chattering and making some weird noises when making left turns.
Maybe you are so focused on your part numbers to be warranty compliant you forgot there is another function of your M6's ATF grade fluid and that is to pressurize the eLSD to regulate your degree of traction and torque bias.
Maybe climb under the car and see that myriad of aluminum tubing leaving your transmission, making one full lap of your car and taking a stop at the rear diff and back... all in the name of "COOLING"!
Here is what you should be using:
https://www.amsoil.com/p/amsoil-sign...on-fluid-atf/?
The GM stuff is junk... a search on any MSDS sheet will share the origin is garbage fleet fluids. Mobil1 is all marketing hype as well. The Driven oil is being used by many racers because their 4th or 5th rebranding campaign from its original Kendall GT is to give racing influencers free products so others will buy it. However... I have yet to see one teardown to show their "High as Giraffe P___Y pricing is any better than Amsoil or Royal Purple's R line.