Vulkan API is continuation of OpenGL, essentially Open Standard equivalent of DirectX.
Nintendo have been using OpenGL for while, this move is important because this means that Nintendo is interested in contributing at setting next-level technology standard.
Bear with me here, because things are about to get a bit technical. Nintendo has recentlyjoined Khronos Group, a non-profit company that focuses on the “creation of royalty-free open standards for parallel computing, graphics and dynamic media on a wide variety of platforms and devices.” Whew. That’s a mouthful. So what does that mean?
It means Nintendo is finally joining a handful of other companies that make sure their devices and hardware are capable of using standardized APIs that have been established in the industry, rather than focusing on proprietary standards. It means less work for Nintendo when it comes to supporting other platforms, and less work for third-party developers who can now use open standards, rather than having to develop their own for specific systems.