What is the keyboard combination on a Chromebook to open the extension menu?

This video on the FAQ page says that you can assign a keyboard shortcut to open the Chrome extenstion menu. In the video, it says that Ctrl + Shift + Space should do it. While it does work on a Windows computer, it does not work on a Chromebook. In the video, it also very briefly shows the user assigning the keyboard shortcut but I cannot find the place to make that change. Whether it can be configured or not, is there a way other than using a mouse to open the extension menu with a keyboard combination?

Any assistance would be appreciated.

This is an unbelievably awesome platform! Thanks to the team who created it.