I found this seemingly-related forum thread belatedly: https://forums.nomachine.com/topic/sound-problem-under-macos-catalina
I did not know to go to the General tab of the Security and Privacy pane after installation, I only enabled nxnode in the Privacy tab. There is no prompt on the General tab.
There is no nxaudio.kext in the /Library/Extensions folder. As you would therefore expect, when I run the command “sudo kextutil -vvv /Library/Extensions/nxaudio.kext”, I get “No such file or directory”. When I run the kextload command you provided (“sudo kextload /Library/Extensions/nxaudio.kext”), I get “/Library/Extensions/nxaudio.kext failed to load – (libkern/kext) not found”.
Is there somewhere from which I can just download the .kext file and then rerun your previous instructions? Or is there some different path to a fix for MacOS 10.14.6?