Many of those types of programs like XRoach, XSnow, XNeko as well as every program rendering to the root window will never be possible with wayland (unless you built them into the display server).
XRoach doesn't work even on a modern X desktop. The background window on, say, gnome, isn't really the root window. I compiled XRoach a few years ago and didn't understand at first why it wasn't working. I don't know if any of the modern desktops have an actual root window that's visible.
You can run a virtual X-Server, like Xephyr or Xnest. They are pretty handy and will make it easy to use root painting programs.
Fun Fact: The XScreensaver "preview" function works (worked?) as following: Start an instance of Xnest and run the screensaver rendering the root window there.