I somewhat recently switched from Edge and had fallen in love with vertical tabs, more specifically an auto-hide favicon'd list that expands when hovered over. This addon was able to fulfill all my vertical tab desires ❤️

More details on their GitHub, if you're like me and want a thin sidebar that expands when moused over: https://github.com/piroor/treestyletab/wiki/Code-snippets-for-custom-style-rules#auto-showhide-sidebar-by-mouseover-hover