Download and install NoMachine's proprietary code in a Debian 11 container. You can then mount your X11 socket in that container and run the NoMachine client, if you want to connect to a NoMachine server.

First, build the container image. The following instructions work for Docker and Podman alike:

git clone https://github.com/apyrgio/docker-nomachine
cd docker-nomachine/
docker build -f Dockerfile -t nx

Then, run the NoMachine client (nxplayer) in the container.

docker run --rm -e DISPLAY=${DISPLAY?} -v /tmp/.X11-unix:/tmp/.X11-unix:ro \
    -e XAUTHORITY=${XAUTHORITY?} -v ${XAUTHORITY?}:${XAUTHORITY}  \ # Remove if no XAUTHORITY file
    nx /usr/NX/bin/nxplayer

Caveats:

• For compatibility reasons, in Wayland systems this will use XWayland (less secure)
• The configuration is amnesiac, meaning that connections are lost after the container exits.
• Rebuilding the container image always pulls the .deb file, in order to verify that the step is cached.