Hi there 
I like to mention that the implementation and maintability of one single graphics library is significantly easier as that one of three or four
Vulkan is everywhere and I see less benefits in the others, including old DirectX. To free up human ressources is crucial in nearly all the projects, so consider to focus on one graphics library.
I guess its possible that I speak to walls
as often in such obvious cases, while I see a chance which lets you consider this option.
Quality creates Quantity
Vice versa is it impossible 