IMO, !$ is most useful of them all (it is the one that gets replaced with the last argument of the last command).

!! you can do just as easily with up-arrow enter, which is just as quick. !ssh you can do with ctrl+r, which actually shows you what it's going to run and whether the last ssh is to where you think it is. sudo !! is up arrow, ctrl+a, 'sudo ', one more keystroke but it's natural if you know your readline. The rest are too complex and not worth learning. !$ is the sweet spot.

I got used to doing this over many many years with the tcsh shell. I switched to Fish recently and I continue to be annoyed by its refusal to implement this feature. Yes, I tried using all the newfangled history-search thingamajigs. They all kind of work, and they all have their issues. But the !, together with in-place expansion, is something I still dearly miss.

i love the mkdir example, so i’m going to exercise that muscle and see where it goes

and yeah ^r works, though i often type a few chars and ^p till i get the match. history-search-backward in your inputrc, iirc

edit: on a computer now :) my `if emacs` block, allowing arrows or ^n/^p to run through history. so for e.g., type "tar" and now as you shift through history with :binding:, it only shows history that began with "tar"

    $if mode=emacs
    "\e[A": history-search-backward
    "\e[B": history-search-forward
    "\C-p": history-search-backward
    "\C-n": history-search-forward
    ...
    $endif