As of 15 January 2018, this is the only add-on that will allow fullscreen functionality with no menu/nav bars on OSX 10.12.6 (FF 57.0.4). The browser.fullscreen.autohide function is broken for this machine configuration.

Feature request for this add-on: please add an icon that can be added to the menu bar that does the CTRL+SHIFT+F shortcut with one click.

It works (mostly) as intended. Four things to note:
1. control+shift+F is the keyboard shortcut, even on a Mac. This is actually very helpful. Since it does not override the default fullscreen behavior, both fullscreen modes are within reach (command+shift+F calls for the default fullscreen behavior).
2. Due to some restrictions it does not work on addons.mozilla.org. This might lead to some false reports saying it does not work.
3. As soon as you do anything in a webpage (click a link, search with Google, etc.), it will revert back to the default fullscreen behavior.
4. It requires access to "all data in all websites", so regular code audits might be needed to ensure that it does not do anything malicious.

I'm afraid I've had the same problem, ctrl+shift+F doesn't work. Using Quantum - 57.0

*Update*: Can't work out how to reply to my own comment. Yes, I needed it for a presentation which I was doing in reveal.js

Didn't work for me. Full screen still had tabs and bar on FF 57 and macOS 10.13.1. Same experience on FF 68 and macOS 10.14.5. Cmd+Shift+F and Cmd+Ctrl+F switches to full screen. Ctrl+Shift+F has no effect.