I'll record a demo this week!
I wouldn't recommend trying it as a standalone window manager right now. Maybe by V3 it should be usable.
I don't know much about EXWM, but I would guess the fact it uses Guile affords different powers than using Elisp.
Also, Guile being the implementation chosen is not incidental, the GNU project is moving towards Guile as an extension language everywhere (The big example here would be GuixSD).