When the Zink Gallium3D driver running OpenGL over Vulkan was first introduced in 2018 and since one of the main blockers besides the performance overhead has been the limited OpenGL 2/3 support. The GL3/GL4 support has been improving with time for Zink and when making use of the latest out-of-tree patches is even possible to get OpenGL 4.6 running over Vulkan with Zink!..

Source: Phoronix – Experimental Zink Patches Get OpenGL 4.6 Running Atop Vulkan