Example workflow: open #Firefox. New tab is already in a temporary container that'll be thrown away when I close it. I can open new tabs anytime, each one is in its own temporary container.
Type "cybre" into a tab and pick https://cybre.space/ from the awesomebar. I've configured a Cyberspace container, so it flips right over to that one where I'm already logged-in.
Click a GitHub link here, it opens in a temporary container. Make a GitHub container, log in. Now all GitHub links open in that container.