Visitors can open Site Search from the keyboard: Cmd+K on Mac or Ctrl+K on Windows, on by default on every page that contains a search box. You can switch the shortcut to the slash key, use both, show or hide the hint chips, or turn shortcuts off, all under Elevated › Site Search › Settings › Advanced Options › Keyboard Shortcuts.
Navigate to Elevated › Site Search › Settings, expand Advanced Options, and locate the Keyboard Shortcuts section.

Enable keyboard shortcuts is on by default. The Shortcut Key dropdown offers Cmd/Ctrl+K, the slash key, or both at once.
Click Save Settings.
Show keyboard hints controls the visual cues: the shortcut chip inside the search box and the Navigate, Open, and Close hints along the bottom of the results. Turn it off for a cleaner box; the shortcuts keep working either way.

The shortcut does nothing on some pages. The shortcut works on pages that load the search box (through the shortcode or the Breakdance element). On pages without a box there is nothing for it to open.
The slash key types instead of opening search. The slash shortcut stays out of the way while you type in a form field; press it with the cursor outside any input.