> I looked at runit but the documentation bills it as a replacement for > init which I find to be very heavyweight. Am I missing something about > runit, like a way to use it to manage a set of processes under init?
It can replace init or it can happily co-exist with it. If you only need service supervision, on most OS's it's just "foopkg install runit". Replacing init is the hard part, very few distros do that (eg. Void).