Xvfb, or X virtual frame buffer is needed by selenium and chromedriver or gekodriver, so it can srun via cron with your PC locked, or without your script taking focus from the user section

[Unit]
Description=X Virtual Frame Buffer Service
After=network.target

[Service]
ExecStart=/usr/bin/Xvfb :99 -screen 0 1024x768x24

[Install]
WantedBy=multi-user.target