It only works if you have an ARM CPU with an NPU.

No, it works on x86-64 assuming the device has a sufficient NPU. Both AMD and Intel CPUs latest CPUs list the Recall preview as available now.

Sure, a subjective 4-part test to determine whether the content is fair use or not. Totally not murky.

Most computers firmware can store a Windows executable. Microsoft pushed for an addition to the ACPI tables called WPBT. That stores a Windows exectuable in the firmware. It is of course totally used for the intended purpose…