Starting a node process synchronously through systemd

Trying to start a nodejs process through systemd as follows :

1 - By creating a foo.service file in /usr/lib/systemd/system/

[Unit]
Description=Foo Service

[Service]
ExecStart=/usr/bin/node /path/to/start.js
WorkingDirectory=/path/to/
Restart=always
RestartSec=10                       # Restart service after 10 seconds if node service crashes
StandardOutput=syslog               # Output to syslog
StandardError=syslog                # Output to syslog
SyslogIdentifier=foo

[Install]
WantedBy=multi-user.target

2 - then by doing :

/usr/bin/systemctl enable foo
/usr/bin/systemctl start foo
/usr/bin/systemctl start nginx

My problem is that I want to start nginx service after foo beccause it requires foo to be up and running.

But the starting of foo.service (which is obviously a nodejs process) is asynchronous so the command line exits right away and then the nginx service starts without the foo finished starting

Is there any possible way to make : systemctl start foo sync ?

ps : Can't use the

After=syslog.target network.target foo.service 

as nginx.service is a file provided by the rpm