I am neither but I'll share my skeptical opinion on the matter.
I believe the iGPU is locked out on both a software and hardware base in these machines,
I've modified BIOS files before to show the settings for running the iGPU in ASUS laptops before and all it's done is crash the system.
Also, it's extremely unlikely for ASUS to go back and make a BIOS change to alter a very important aspect of the system.
There's just no way, no computer company would do this, in my opinion. There's laptops I've seen in the past that can have either one of the GPUs running but without mixing through Optimus, which doesn't help either because for this feature, both need to be enabled at the same time. Either way, it seems impossible. At best, ASUS will make a new laptop that can support this once the feature becomes available. Probably gonna be one of the next G-series generations.