xdmx 2:1.20.8-2ubuntu2 (arm64 binary) in ubuntu focal

 Xdmx is a proxy X server that uses one or more other X servers as its
 display device(s). It provides multi-head X functionality for displays that
 might be located on different machines. Xdmx functions as a front-end X server
 that acts as a proxy to a set of back-end X servers. All of the visible
 rendering is passed to the back-end X servers. Clients connect to the Xdmx
 front-end, and everything appears as it would in a regular multi-head
 configuration. If Xinerama is enabled (e.g., with +xinerama on the command
 line), the clients see a single large screen.
 .
 More information about X.Org can be found at:
 <URL:https://www.x.org>
 .
 This package is built from the X.org xserver module.