I'm running FreeBSD myself and there is in fact a working Wayland stack. THe only issue is that the KDE integration is currently broken so I can't use it. But I've been told by people using other DE's and WMs like sway that it works great.

But yes X is a great common denominator. I used it back in the 90s with Xappeal on DOS. Was great at college when we ran out of free X terminals.