I followed the steps in the readme and after sshing into the container I tried to run xeyes and it didn't work (error was something like "no server"). After a quick search I learned that the more recent OS X versions don't come with an X11 app, and you need to install XQartz (https://www.xquartz.org/) for things to work. Might be worth mentioning in the readme since you do talk about using this approach on a mac.
I followed the steps in the readme and after sshing into the container I tried to run xeyes and it didn't work (error was something like "no server"). After a quick search I learned that the more recent OS X versions don't come with an X11 app, and you need to install XQartz (https://www.xquartz.org/) for things to work. Might be worth mentioning in the readme since you do talk about using this approach on a mac.