Tested the dump1090-fa init script installation from github on another Debian based OS “Devuan” which lacks systemd. Found works OK
https://www.devuan.org/
https://www.devuan.org/get-devuan
devuan_chimaera_4.0.0_amd64_desktop-live.iso
After installing dump1090-fa, installed dump1090-fa init file /etc/init.d/dump1090-fa
by following method:
sudo wget -O /etc/init.d/dump1090-fa https://github.com/abcd567a/dump1090-fa-init.d/raw/main/dump1090-fa
sudo chmod +x /etc/init.d/dump1090-fa
sudo update-rc.d dump1090-fa defaults
sudo /etc/init.d/dump1090-fa start
sudo /etc/init.d/dump1090-fa status
cat /var/log/dump1090-fa.log