We've previously reported that the Vulkan 1.0 conformant V3DK driver for Raspberry Pi 4 and other Broadcom BCM2711 based platforms was part of Mesa 20.3 open-source graphics framework. But at the time, it was still under development.
The good news is that Mesa 20.3 has now been released, and there's much more than Raspberry Pi 4 support, as Collabora informed us the release also included Arm Mali Bifrost GPU support via the open-source Panfrost driver.
The latter was made possible thanks to the work by Alyssa Rosenzweig and Boris Brezillon, with Alyssa going into details in a recent blog