Apple's GPUs support a decent chunk of the Vulkan featureset, you can go boot it up on an M1 with Asahi. Same goes for OpenXR. These are things that Apple neglects because they want to use their customerbase as leverage to market proprietary APIs. This hurts users, because Apple has neither industry-leading standards nor the leverage to force the industry to adapt. And they sure as hell lack the humility to just support both in the name of fair competition.