In the Mu Editor there are some built-in tools for easily making Graphical User Interfaces and Games.
For games there is PyGame Zero (internal link), which is a much easier way to get started with PyGame.
For GUIs there is GUIZero, which is a nicer wrapping around Tkinter.
TODO add some quick tutorials here! Until then, link dump!
There is a potential problem with Tkinter and thus GUI Zero on some modern Macs - button text will not show until window is refreshed by a resize: