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?
Besides what others have said with Ctrl+L then Ctrl+C, you could use an extension for custom shortcuts like this:
https://github.com/crittermike/shortkeys
https://www.shortkeys.app/
And I checked and their is an option that you can set to copy url of the page you are on.