since you are a wl dev would it be possible to give an answer on what parts of wayland are missing in order for it to be able to support a full desktop environment??
Not really, sorry. I haven't worked with desktops enough to know what they need. You might get some idea, if you take the EWMH spec and assume everything is still missing. You might also add ICCCM, but AFAIU that is less relevant here, since the display server and window manager are the same process, and they actually contain policy, too, which the X server does not.
Note, that EWMH is not supposed to be implemented directly. EWMH is for X, and Wayland is way different. But we do need lots of similar features, and those are pretty much missing.
Also, I haven't looked at what the KDE, Gnome or other specific desktop projects have done, all I know at this time is the wayland demos.