Mirror Hall is an experimental app that aims to turn any Linux device into a second monitor.
It is designed on both desktop and mobile devices, and supports both hardware-accelerated and software-based encoding to stream video efficiently.
Mirror Hall makes use of a new, experimental GNOME feature to create virtual monitors, and requires UDP traffic to be allowed by the network and firewall. Support for other desktops will be added once a standardized API exists.
Better error handling, improved UX, warnings when using experimental APIs, and a new icon (thanks Tobias).