I would assume all linux GPU drivers would need to be adapted at least a little to support the larger page size (most linux AARCH64 kernel level code is writing assuming 4kb pages).
If apple were found to be in violation of Patent misuses the result would not be that apple is forced to open up the internals of how their products work but rather that patens apple has would be make null and void and others could copy them (based on the already public patent filling and nothing more).
The big issue with this is apple does not own all of the IP in a any of their hardware, much of it is a mixture of licenses from many vendors some of it owned by apple much of it just licensed.
Apples licenses for these will include very strict NDA clauses that make it impossible for apple to share the documentation they are provided but that vendor.
As described in the article by not having fixed function units apple can put more regular floating point math units. These units can be used in many, for example when doing compute tasks or when doing 3d tasks that do not make use of those very focused use cases. In the end if it is a big perf hit for those approaches devs will just use different solutions as they need to developer explicitly for metal anyway.
Why should they support vulkan? what does apple get out of that apart from less well optimised compute and shader code, using more battery and producing more heat for the same output. (the reason it would be less well optimised is Vulkan is an API designed by a group to be the best compromise of many GPU vendors.
If apple wanted to support vulkan without it being worse than Metal they would either need to add so many apple only extensions that it would be Vulkan in name only or make their GPUs be identical to AMD or Nvidia (unfortunately due to IP patents apple can't just make a copy of AMDs GPUs they need to find another IP partner and that is PowerVR).
If PowerVR had 80% of the GPU market (like Nvidia) the would have pushed Vulkan to line up with a TBDR pipeline but they do not so while you can run Vulkan on a TBDR pipeline you end up throwing away lots and lots of optimisations.