This add-on is awesome! Chrome/Opera/Brave/Edge cannot do this even if they wish. As of now - some of them allows sidebar, but just for viewing Bookmarks or displaying search-results.

Only Firefox can pull-up a website in a sidebar as of now. Please continue its development.

This feature is "one" more major reason to totally ignore other web browsers in my day-to-day work. I have always used Firefox and will continue supporting it. Thanks for the continued development of the Mozilla project. God bless. Cheers.