How can I install VNC server on NomadBSD and what are the steps to open appropriate ports on its firewall so that I could connect to its desktop?
NomadBSD is FreeBSD, you can google for:
install vnc server site:freebsd.org
just install novnc, the docs are decent. ports to open would be 5800-5900 if you don’t like websockets or a web UI based vnc server/client then another option is tigervnc. Also responding with a link to google is like waiting 45 mins in a livechat at a company and just being told to dial a 800 number.