That's more a matter of buffer management. Though it may turn out , if their work is too tied to NVIDIA, to only support NVIDIA's de facto proprietary selection

That's more a matter of buffer management. Though it may turn out , if their work is too tied to NVIDIA, to only support NVIDIA's de facto proprietary selection: EGLStreams. Though in principle, there's nothing preventing them from using GBM instead of EGLStreams, and there are some good practical reasons such as having compatibility with the broad base of existing accelerated Wayland windowing libraries and applications.