Debian has also had Debian GNU/Hurd in unstable state for years. That Gentoo/FreeBSD page mentions that the port is "experimental" and "incomplete". So presumab

Debian has also had Debian GNU/Hurd in unstable state for years. That Gentoo/FreeBSD page mentions that the port is "experimental" and "incomplete". So presumably they're talking about a non-Linux kernel as a first-class component in a stable release.