Gallium is not used in Vulkan drivers. But Zink (OpenGL on top of Vulkan) does use Gallium, so with NVK, if you want OpenGL you can use Zink which uses Gallium.

Gallium is not used in Vulkan drivers. But Zink (OpenGL on top of Vulkan) does use Gallium, so with NVK, if you want OpenGL you can use Zink which uses Gallium. Edit: Gallium is not only not deprecated, but it's also used by basically every GL driver withing Mesa these days.