Edit: Commenters say long-pressing reveals a URL without opening it in mobile browsers, which is nice to know. I only have experience with using regular desktop FF on my (Linux) phone, which doesn't support such a thing AFAICT.
Worked fine on mine (chrome on Android): touch and hold and wait for pop up. If the link in the upper right is cut short with an ellipsis, touching the link will expand it, just like ellipsis shortened alt texts.
Depends on the device and software. At least on my phone's Firefox browser a long-press of a link will bring up a menu that includes the URL (though it can run into space constraints for long URLs).
Edit: Commenters say long-pressing reveals a URL without opening it in mobile browsers, which is nice to know. I only have experience with using regular desktop FF on my (Linux) phone, which doesn't support such a thing AFAICT.