Mir is a pretty notable example. In 2013, around the same time development on Wayland sessions was picking up for the other desktops, Canonical decided to try doing their own incompatible thing and designed their own display server system to replace X for the then-upcoming version of their Unity desktop.
Ubuntu switched from Unity 7 to Gnome 3 before Unity 8 and Mir were ready, leaving both projects abandoned by Canonical and handed off to the community. Long after it had already lost what little relevance it had, Mir eventually was converted into a Wayland compositor.
- Technically Wayland isn’t a display server. It’s a protocol compositors implement.
- Technically, xorg is a fork of an older x11 project.
- No.
There is pheonix, and it is written fully in zig. I think it is a X11 protocol built from scratch, but will include modern features like HDR and VRR. It will also become compatible with Wayland apps along the way. I do not know the status, and I did not do much research on it.
https://github.com/ValveSoftware/gamescope
Not that useful, but the answer is Yes.
