On the desktop app, when one hovers over the “Open in Companion Chat” button (see image below) in the top right of the chat interface, perhaps for improved UX it should display your bound keybind after a short hover. Other buttons already do this in the companion chat itself once you have content in it e.g. Open in Main Window (⌘O) and New Chat (⌘N).
Hovering over this for some short while would reveal a small text window that says “⌥Space” by default, otherwise whatever one changed it to in settings.