I've been wondering why the pkgsrc project hasn't held a "fly-off" between pkgin and nih in order to select an official package manager, and then integrate this directly into the mk/* framework such that the very first package built is this official package manager.
For pkgsrc, it seems like having an integrated binary package manager would "fix" the problems seen with the "experimental" "make replace"
and untrustworthy pkg_rolling-replace.
Now, not having used either pkgin or nih, I'm only assuming one or both of them are similar to pkgng where they have their own database and internally store package metadata which is why it needs to be built first.