I have created mullvad-vpn-openrc with script (http://github.com/goose121/initify) .
This was my first time. Tell me if I did any mistake :).
Link: mullvad-vpn-openrc (https://github.com/Luciogi/artix_pkg/tree/main/mullvad-vpn-openrc)
There's a much more complete online systemd-to-openrc script converter at http://openrc.run
Thank you. It is very useful.