I just went through a long list of keyboard shortcuts for Firefox. One that I didn’t see that I would find useful is to press something like ⇧ Shift + ⌘ + C to copy the URL and then paste it into an email or message to send to someone. Does something like this exist?
Ctrl +L will move your cursor to the URL bar and select the address, and you can Ctrl+C from there. Should work on a Mac but may need to use cloverleaf button instead of ctrl.