I think what you want is in Firefox nightly right now: https://blog.nightly.mozilla.org/2024/08/07/firefox-sidebar-and-vertical-tabs-try-them-out-in-nightly-firefox-labs-131/
That expands and compacts based on the sidebar state and can be flipped to the right side of the window in the ‘customise sidebar’ settings.
Plus it did land on the barge. Most of the debris should be there, though the remaining fuel would have mainly gone overboard. Probably the flight termination explosives also.