nx-x11proto-core-dev binary package in Ubuntu Mantic arm64

 NX is a software suite which implements very efficient
 compression of the X11 protocol. This increases performance when
 using X applications over a network, especially a slow one.
 .
 This package provides development headers describing the wire protocol
 for the core nx-X11 protocol, and also provides a number of utility headers,
 used to abstract OS-specific functions.

Source package