Wayland seems ready to me but the main problem that many programs are not configured / compiled to support it. Why is that? I know it's not easy as "Wayland support? Yes" (but in many cases adding a flag is enough but maybe it's not a perfect support). What am I missing? Even Blender says if it fails to use Wayland it will use X11.
When Wayland is detected, it is the preferred system, otherwise X11 will be used
Blender's Wayland support is not great because they're doing stuff from scratch. They're not using an existing toolkit like GTK, Qt, Electron, or even something like SDL to get Wayland support.
But if you're using an existing toolkit things are much easier and support is automatically there, you just need to do testing to ensure everything works.
The common biggest things that still use Xwayland are Chromium based apps and programs running under wine/proton. Chromium has an experimental Wayland mode that works well enough, but definitely has some bugs, especially around windowing. Wine Wayland is in the works.
Wine and Proton have actually put a ton of work into Wayland support, it's very far along. I wouldn't be surprised for Proton to have a native Wayland version soon.