Persistent window
Press ⌘ 3 times to open the persistent window. When switching application, the hotkeys list will be updated shortly after.
Press ⌘ 3 times to close the window.

ShowMeYourHotKeys shows all the menu items hotkeys of the app you are using — instantly, on macOS.

One command and you're ready.
$ brew install --cask showmeyourhotkeys
Press ⌘ 3 times to open the persistent window. When switching application, the hotkeys list will be updated shortly after.
Press ⌘ 3 times to close the window.
Hold down ⌘ to show the instant window.
Release all keys to close the window.
Filter the hotkeys list on menu title and/or on modifier keys (⌘ ⌥ ⌃ ⇧ or fn).
Change menu items shortcuts.
Assign a shortcut to menu items that don't have one. (Some applications do not support custom hotkeys.)
Bookmark a hotkey so that it always appears at the top of the list and is never filtered out.
Show hotkeys on screen while typing.
System hotkeys are displayed at the end of the list. They can be filtered like other hotkeys.
The list is updated if changes occur in System Preferences.
Everything included
Use the persistent window or the temporary “long-press” window. Choose among four available window layouts.
Filter app hotkeys to quickly find the one you are looking for.
Bookmark your favorite app hotkeys. ShowMeYourHotKeys will always show them on top of the list.
Define how and when ShowMeYourHotKeys will show hotkeys.
Browse all hotkeys of your applications.
Generate PDF cheat sheets of your applications shortcuts.
Display keys on screen while typing.
Define your own custom hotkeys for applications menu items.
Display all system hotkeys.