Being a Khronos standard doesn't mean it exists anywhere.
EGLStreams doesn't exist on Windows, as Windows doesn't have any EGL at all. Similarly while EGL is used on Android, Android doesn't support EGLStreams and probably won't as the functionality already exists & EGL is on the way out long-term as Vulkan adoption picks up.
With all that said, EGLStreams is probably also not going to get adoption on most platforms as it's pretty terrible & inferior to what most platforms already have. Which is, on most platforms you can work directly with buffers instead of being forced into a specific point to point pipe (Android's HardwareBuffe or iOS/Mac's CVPixelBuffer)
