A while back there was some discussion on setting up runit/sysv scripts, etc. for programs.
I ran across this the other day and thought it might be useful. MX Linux uses it to convert systemd scripts to sysVinit on their non-systemd installs.
Maybe you are familiar with it already.

FWIW- https://github.com/RosstheRoss/sysd2v

Cheers!