This is cool, though its a shame how reduced Safari's extension interface is.

Arc appears to take this to the next level and makes all tabs, spaces, windows, notes, easels, web search, and commands available to the command palette shortcut that conventionally opens a new tab elsewhere, Ctrl-T/Cmd-T. I think this is definitely the next step in browser UI, but this extension is probably how far Safari will let you go until they implement it themselves.