I built HARM, an open-source Android app that turns an old tablet into a focused camera and media display controlled by Home Assistant automations. RTSP/HTTP playback and remote screen control work across the local network without showing the HA dashboard.
Website and APK: https://harm-app.github.io/
Source: GitHub - harm-app/harm: Local-first Android camera and media display controlled by Home Assistant · GitHub
Feel free to try it, adapt the code to your setup, and leave feedback or suggestions. Contributions are welcome!