Besides Zink, there is GL ES support on top of Vulkan through GLOVE[1] as well as Google's own ANGLE[2].
[1]: https://github.com/Think-Silicon/GLOVE [2]: https://github.com/google/angle
Zink is an effort to write an OpenGL layer on top of Vulkan. Previous discussion:
But it's not. Where is this OpenGL implementation that runs on Vulkan? I would argue that it should come as fully open source from Khronos group since they are the ones providing both standards. It's fine to create a new thing with a long term vision of what a better world looks like. But people won't follow if the pieces they need today are just a wish.