Unrelated to your question but why do people hate Wayland?

There is arcan which is its own thing. I'm not aware of any mature application using it for the desktop though.

Otherwise if you assume that every wayland compositor basically endorse the role of a display server, there are plenty of them.

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.

Yes, NeWS (Network extensible Window System) from Sun Microsystems but it hasn't been maintained for years and had commercial licensing fees, and DirectFB used in embedded systems.

And as others mentioned Mir from Canonical which now implements the Wayland protocol.

1. Technically Wayland isn't a display server. It's a protocol compositors implement.
2. Technically, xorg is a fork of an older x11 project.
3. 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.