CheatSheet shows you the available shortcuts of the active application after holding the command-key for 2 seconds.
CheatSheet vs KeyCue opinions
People love CheatSheet because it's simple to use, but mostly because it's free.
It's free and it works with High Sierra.
With Paletro, by pressing ??P, you have access to all of the functionality of current focused app, including keyboard shortcuts for the most common operations.
Paletro vs KeyCue opinions
Paletro is just as nice/powerful as KeyCue IMO at less than half the price. It's also included in Setapp if you subscribe to that.
KeyCombiner helps you learn exactly the keyboard shortcuts you need. Create your own shortcut collections by importing from a large public database of shortcuts (VSCode, Vim, IntelliJ, Gmail, Notion, Excel, etc.
WinExt Key Launcher is used to quickly open your resources by shortcut keys, you can press two keys (Ctrl+? or Alt+?) at any place of Windows to open the corresponding resource during it is running.