Start a script as a service

sudo nano /etc/systemd/system/ptcam-app.service

Create an ini file

[Unit]
Description=PanTilt Camera Web App
After=network-online.target
Wants=network-online.target

[Service]
User=sophior
WorkingDirectory=/home/sophior/pt_rpi
ExecStart=/home/sophior/pt_rpi/venv/bin/python -u /home/sophior/pt_rpi/app.py
Restart=always
RestartSec=5

[Install]
WantedBy=multi-user.target

Start

sudo systemctl daemon-reload
sudo systemctl enable ptcam-app.service
sudo systemctl start ptcam-app.service

Check logs

journalctl -u ptcam-app.service -f

Stop/restart

sudo systemctl restart ptcam-app.service