If your device has an unused VGA connector, then on X11 (perhaps Wayland too) you can "force" the graphics-card into a mode for that output without connecting a VGA dummy plug.
That second screen you just export with X11vnc.
Using Android Phones/tablets, and USB connections, you can do some little "adb forward" magic, and then push the VNC stream over the USB-connection to a VNC viewer on the Android tables.
Run x2vnc to "beam" pointer/HID data to the tablet, for when you are on the external screens with the mouse.
Works fine, very low latency, no WIFI required. And it charges your tablet too.
For Linux, X11, USB-connection to Android-Device(s), and the TV over Network:
- Make another screen - 3 options, depending on driver/available_outputs:
1: make a mode with `cvt`, add it with `xrandr --newmode`, bind it to unused output with `--addmode`
2: Use a dummy plug on a free output
3: Use `evdi` and the `example` application in evdipp to create a virtual screen, attach the provider with xrandr
- Export the new screen, or a portion of it with `x11vnc`, using the `-clip` option with coordinates or screennumber.
Optional: Use `NoVNC` to make VNC available to any HTML5 browser
- use adb port forwarding commands to forward localhost:whatever1 on the Android device to connect to the X11VNC port.
- Use ADB, or your finger to start VNC session on tablet to localhost:whatever1, and UPNP/whatever to start browser on TV for NoVNC url.
That should cut down your research time ;)
Be warned, Evdi&EvdiPP are currently still glitchy, but under active development.
That second screen you just export with X11vnc.
Using Android Phones/tablets, and USB connections, you can do some little "adb forward" magic, and then push the VNC stream over the USB-connection to a VNC viewer on the Android tables.
Run x2vnc to "beam" pointer/HID data to the tablet, for when you are on the external screens with the mouse.
Works fine, very low latency, no WIFI required. And it charges your tablet too.