Yes you can, wlroots has an extension for that, that will work on every “niche” wm based on it. You could not really get a system panel to work on plasma and gnome as well on X.

> Can you have one client talk to another client?

It is way too vague (generally, what does it have to do with the display manager? Pipes, IPC, dbus), but if it means something like drag’n’drop, it is supported.

> Can you turn on your computer and do anything even remotely productive with it? No, you should not want to be productive

This is just utterly stupid.