Despite claiming to be configurable on a per-site basis, I was unable to determine how to do this (extensive searching). And, if the extension's icon is supposed to be visible, it is not on my system (FF 121.0), and while I can find it in the overflow "Extensions" button on the toolbar, it is greyed-out and unresponsive. I uninstalled it after an hour, as I need its capabilities for ONE site, not all sites, and it does not appear to have this capability.

I don't know what to think as there is no icon available at all anywhere so I can't say it installed correctly. I bookmarked the options page so I could get to that but the hide icon is unchecked so it should be there I would think. If there is no icon is it not installed correctly?
Edit: I did find it in the dropdown menu where the three dots (...) are in the site address. If you right click on it you get the option to remove it form the address bar or manage it. If you remove it does it show up in the tool bar?

Fake location doesn't work with Firefox 60.
Not even with this extension demo.