Still the same basic gotcha.
Linux requires a collaborative effort between the kernel developers and the hardware /GPU driver teams, and an agreed upon API to access GPU memory across process boundaries.
Apple was able to do that via IOSurface for us. I believe that it required specific collaboration with Nvidia, intel, ATI, Imgtec, and other GPU vendors in Apples ecosystem to ensure it works.
I don’t believe linux/the community has this capability, or a need / desire for it.