A GTKWave version for Ubuntu can be installed in Ubuntu, by giving the command
sudo apt-get install gtkwave
The program can then be started by giving the command gtkwave.
We can download a GTKWave version for Mac, in the form of a zip-file that contains an app folder with an executable GTKWave program.
The GTKWave program can be started from the GUI via Mac-right-clicking on the app folder (the app icon) of the program and selecting Open - to indicate that you are sure that you want to open it.
It can also be started from a Terminal, by giving a command indicating the name of the executable gtkwave program.
Having installed gtkwave in the folder (you can copy either the zip file or the unzipped content to the folder)
$HOME/sw/gtkwave
I could start the program by doing
$HOME/sw/gtkwave/gtkwave.app/Contents/Resources/bin/gtkwave