Per AMD
>Notably, AMD's closed-source Vulkan driver currently uses a different pipeline compiler, which is the major difference between AMD's open-source and closed-source Vulkan drivers.
When the fears are unfounded the reason isn't "Nvidia/Intel could find out things about the hardware", it's "incompetence rooted in believing something that isn't true". Which is an entirely different thing because in one case they would have a proper dilemma and in the other they would need only extricate their cranium from their rectum.
Good luck trying to explain that to Legal. The problem at the core with everything FOSS is the patent and patent licensing minefield. Hardware patents are already risky enough to get torched by some "submarine patent" troll, the US adds software patents to that mix. And even if you think you got all the licenses you need, it might be the case that the licensing terms ban you from developing FOSS drivers/software implementing the patent, or that you got a situation like the HDMI2/HDCP situation where the DRM <insert derogatory term here> insist on keeping their shit secret, or you got regulatory requirements on RF emissions.
And unless you got backing from someone very high up the chain, Corporate Legal will default to denying your request for FOSS work if there is even a slight chance it might pose a legal risk for the company.