allows me to control the desktop of my Ubuntu machines from a MAC. the software of choice is X11VNC – reasonably easy to enable just a few stumbles to get it to load at boot – code below is copied from here https://tecadmin.net/setup-x11vnc-server-on-ubuntu-linuxmint/

1. make file x11vnc.service in /etc/systemd/system :
gksudo gedit /etc/systemd/system/x11vnc.service 

[Unit]
Description=x11vnc remote desktop server
After=multi-user.target

[Service]
Type=simple
ExecStart=/usr/bin/x11vnc -auth guess -forever -loop -noxdamage -repeat -rfbauth /home/****/.vnc/passwd -rfbport 5900 -shared

Restart=on-failure

[Install]
WantedBy=multi-user.target

2. sudo systemctl daemon-reload
sudo systemctl start x11vnc
sudo systemctl status x11vnc

3. if it’s worked
sudo systemctl enable x11vnc.service

et voila