[simcop2387]

For linux, check out firejail for isolating it.

[pmontra]

I didn't know about firejail. Thanks.

The gist of it is

  sudo apt install firejail
  firejail audacity

I guess that the line

  net none

in /etc/firejail/audacity.profile prevents any network connections. And

  man firejail

for many useful functionalities.