Since systemd liked to muck up my IPv6 routing, I've been looking for an alternative Linux distro to run on my RasPi 2, running Devuan for a while before getting sick of the missing Debian packages that it didn't provide, despite a lot of them not even being dependant on systemd.
Long story short, I ended up on Arch/Parabola. Pihole is fortunately provided as a custom build on the AUR, but there's nothing accounting for alternative init systems. Until now! I've been writing a rudimentary startup script for FTL that more or less adheres to the OpenRC conventions. I've also uploaded a PKGBUILD formula to the AUR for quicker installation.
If you're more experienced in writing OpenRC scripts, feel free to fork and request a pull! I'm sure there's still a few things that can be improved.
Also, the main 'pihole' script will need updating of its restart function to the OpenRC equivalent of the systemd commands that are already present, but that's a quick edit which I think doesn't necessarily need a github repo. Maybe I'll make a little .patch file with a PKGBUILD formula at some point.