The Shortcut VUr addon for Blender shows on the left of the 3D viewport 3 mouse buttons that the keystroke that has been pressed. This is pretty convenient for when you post some tutorials on YouTube. The addons shows keystrokes, but as far as I could try it out, it doesn’t show keystrokes like G Y (Grab on the Y axis). It simply shows G in that case. It shows shift-G, Ctrl-G etc, and Alt – Leftmouse, shift – leftmouse and such combinations.

Screenshot of the shortcut_VUr  addon by Jayanam for blender 2.8.
Display mouse and keyboard input in the viewport.