DX over Vulkan for non-windows is being worked on too, just not by Khronos:
https://github.com/disks86/VK9
https://github.com/doitsujin/dxvk
and VKD3D for DX12 on Wine
Windows supports Vulkan but to get onto the Windows Store you can only use DX12.
> While Windows, unlike macOS, does have Vulkan drivers from GPU companies, applications sold through the Microsoft Store are only permitted to use DirectX.
You as a user can move to Linux, and game developers should support Linux, but a game which can only be played on Linux and *BSD will be incredibly unsuccessful.
I just got new laptops that will support both GVT-G and PCI passthrough via OVMF so that I can run my bloatware OS in a KVM VM but still get full 3D acceleration. Hopefully Microsoft decides to contribute heavily back to Wine, or maybe open source their 4GB spyware beast to understand what it is actually doing that makes it so large compared to my distro, which does everything Windows does in much less resources both storage and compute.