Its likely easier to implement a debian-like alternatives system (by hand or by ansible with symlinks if necessary) than to turn a Debian/SystemD non-unix into something unix-like such as Freebsd. Or Freebsd is much closer to what I want, than Debian, so logically it would be easier to change a little bit of Freebsd than a whole lot of Debian.
Of course, Debian/kFreeBSD is an ambitious project - and probably not what you want if you would rather run FreeBSD -- but Debian/kFreeBSD already exists (I'm not sure of the status of Stretch and/or support for the FreeBSD 11 kernel etc):
We'll, there's always Debian/kFreeBSD for that...