Are the abbreviation tooltips written by hand or generated programmatically? In "Total Cookie Protection (TCP)" it says TCP stands for Transmission Control Protocol.
Firefox has left me scratching my head a few times, I think they limit the amount of fallback fonts to resist fingerprinting. Long lists like these will get cut short. Text you intended to be monospace might not be rendered as such as the "monospace" at the very end was never reached.
Alt-x does the very same in Emacs. Every available command with tab completion and with the keyboard shortcut listed. I think showing the shortcut is new.
If you are not familiar what a particular command does you can use C-h f <function-name> to open the help page.
I think Emacs is really easy to learn after you get a handle of the navigation keys. Which you might already be familiar with from shell.