TruePlay will obviously work only with UWP applications, standard applications (from Steam, Origins, etc) are not affected.
Built-in firmware is a very deep and generic way of detecting cheats. I think it would require a kernel driver to communicate with it.
Hooking the kernel function MmCopyVirtualMemory by checking if the target process is the game would already be a step to eliminate cheats in most situations (dynamic dll injection, dynamic read/write process memory writing).
It is possible to overwrite a kernel function in ring0 by manipulating through the cr0 register, and then write code to this function to jump to a custom function. But this is an extremely dangerous situation as it could cause an hang/bluescreen if not hooked correctly.
I already thought of a way to avoid this kernel protection in user-mode, but it's better to stay quiet.