The official Vulkan API Conformant Products list from The Khronos Group recently had Valve's Steam Machine appear on it - so a release is likely quite soon.
We're seeing excitement build up from the Vulkan API release 1.4.340, with a new extension that should eventually improve DirectX performance on Linux.
The D7VK project for providing Direct3D 7 support on Linux with Wine / Proton has expanded in the version 1.1 release to add experimental Direct3D 6 support.
While OpenTESArena is still a work in progress to bring The Elder Scrolls: Arena up to modern standards, it's looking even better with the 0.17.0 update.
For a while now Linux users with NVIDIA GPUs have been reporting performance issues with DirectX12 titles using VKD3D, but a fix may finally be coming.