If you need extra customization capabilities, just run a shell script via the ExecStart= parameter and boom, you have all the power of systemd and the shell combined.
You can even do one better since systemd can natively run rc scripts. If you're on a systemd based distro peak at /etc/init.d. You can even manage services with /etc/init.d and the service command.
The amount of effort systemd went through to make existing software work is genuinely heroic.
The amount of effort systemd went through to make existing software work is genuinely heroic.