Imitations sneak into above-the-table supply streams all the time. The bootlegger need only imitate the package shape and markings, and even knowledgeable people may not notice.
Chips as complex as SoC's having GPUs are being produced by counterfeiters who are not just copying the package and artwork, but actually making clones working only from published documentation and redistributable drivers?
But they would be thwarted by license agreements making the drivers generally nonredistributable?
It definitely is something that usually happens to simpler chips that are easy to reproduce. I'm not even trying to say it is likely that someone is or would bootleg the SoCs- just that the earlier argument that there wouldn't be any black-market buyers is irrelevant, because bootleg parts make their way in to legitimate supply streams all the time.
But they would be thwarted by license agreements making the drivers generally nonredistributable?