It would be really helpful if the TGZ archive for the GIMP plug-in included a README or INSTALLATION file in plain text format that describes how to install G’MIC for GIMP on OS X.
+1 for this excellent suggestion. Currently, installation for a first-timer is complete guesswork. I just gave up.
@David_Tschumperle maybe you should add one line in your Download page for MacOS users?
tar -xC ~/Library/Application\ Support/GIMP/2.10/plug-ins/ GMIC-Gimp-2.10-OSX.tgz