They're working with Canonical to make sure that it's well supported, and they chose them because Ubuntu in particular is focusing on making Linux for the mains

They're working with Canonical to make sure that it's well supported, and they chose them because Ubuntu in particular is focusing on making Linux for the mainstream. In this context, "supported" on a particular platform doesn't mean "can run," it means "should work out of the box for absolutely everyone." I have no doubt that, come the release on Ubuntu, unofficial packages will come into being for nearly every distro--and on Debian you probably won't even need that.