@karthink If you're curious, I've bound s to a command to type the login and password for the selected password-store record with xdotool :-)

Ivy allows passing the `:keymap' parameter to `ivy-read', which is joined with `ivy-minibuffer-map'. So adding a custom command is as simple as:

(defun my/test-command ()
(interactive)
(ivy-exit-with-action
(lambda (entry)
(message "Selected: %s" entry))))

(defvar my/test-map
(let ((map (make-sparse-keymap)))
(define-key map (kbd "M-t") #'my/test-command)
map))

(ivy-read "Foo: " '("foo" "bar" "baz")
:keymap my/test-map)

Pressing M-t in the completion buffer will invoke the lambda inside `my/test-command' on the selected entry. However, it will also continue the normal execution flow after `ivy-read'.

I probably wasn't specific enough; `ivy-read' also has the `:action' parameter, entries of which take two keystrokes to invoke: one for `ivy-read-action' and one for the action itself, much like Embark. The `:keymap' functionality is distinct from this, although packages usually configure both `:action' and `:keymap' to one set of keys and commands.

Well, now it seems I don't need that knowledge anymore :-) I'll probably go with binding `kmacro' for now, as @oantolin suggested. And then try to hack something more general.