A NVIDIA Engineer In His Spare Time Wrote A Vulkan Driver That Works On Older Raspberry Pi
While there has been a Vulkan driver in development for the Raspberry Pi 4 and future models with the newer Broadcom VideoCore GPU that officially supports Vulkan, an independent developer has been developing a Vulkan driver for the VideoCore IV GPU found in pre-RPi4 SBCs. VideoCore 4 isn't compliant with Vulkan in full, but with enough effort, a Vulkan driver was brought up.
This new RPi-VK-Driver was developed over the past two years by Martin Thomas, a graphics engineer currently working for NVIDIA who developed this driver in his spare time. It reportedly took about two years to get this unofficial Vulkan driver into shape for Friday's "1.0" release.
This unofficial Vulkan driver for VideoCore IV implements a subset of the API and various hardware limitations encountered but enough that the likes of vkQuake3 can run on the driver with good speed. Performance compared to the VC4 OpenGL driver is quite good thanks to better memory management, multi-threaded command submission, and other improvements.
More details on this Raspberry Pi Vulkan driver for older boards via this GitHub repository.