Doesn't really matter...
OpenGL and Vulkan work more-or-less the same way., that regardless of the version of the SDK you build with; what version(s) it's compatible with is determined by the features you use.
As AppGameKit is hard limited to features available in OpenGL ES 1.1; this means it'll run on anything that has OpenGL / OpenGL ES / Vulkan Support.
This said, it also means that outside of some performance differences., there really isn't any real reason to use Vulkan beyond it is the Default Renderer for AppGameKit Studio... even then *IF* your target system doesn't support Vulkan, only OpenGL; it'll automatically "Fallback" to OpenGL as the Renderer.
Even in regarding performance differences., it isn't a clear cut "Vulkan is Faster"... somewhat depends on Hardware, Drivers and what you're doing.
The only different I recall there being is with how you use Render Images (Targets) as Vulkan requires them to be dedicated, while OpenGL can use them freely; it's a little extra setup to support and really most are unlikely to run into the issue.
