The issue isn't as much of proprietary drivers as nvidia not wanting to implement GBM in their drivers as it's supposed to for wayland support and pushing for EGL streams.

It means that people writing wayland compositors have to write a EGL stream version because of a purely one-sided nvidia decision.

EGL Stream support in Mutter (gnome) is supported a bit by Nvidia but that's it.

Between spending time on improving a compositor and the window managers making use of it or spending time to support non standard driver implementation because of one-sided decision from nvidia, it seems to me that the first choice is a smarter one.