Croteam have recently released both Serious Sam VR: The First Encounter & Serious Sam VR: The Second Encounter on Steam. They both use their new Fusion engine which comes with Linux support, Vulkan and 64bit.
OpenXR is the official name of the Khronos Group's new standard for virtual reality and augmented reality. Hopefully we will see Valve and other companies move towards this instead of their own implementations.
EGOSOFT, who became pretty Linux-friendly in recent times are working on two new space simulation games! X Rebirth VR Edition will use Vulkan and they are starting to plan X4.
Khronos announced today that they are working on a new open standard for VR and Valve have already said they expect replace parts of their OpenVR with it.