Design pattern 1 the one shot
Use this design pattern to show a window, get some input values and then close the window. The window is not meant to stick around for very long.
An exciting development in 2019 was the addition of the close parameter to the window.read() call. This enables you to write single line GUIs (again), a capability that was around in the early days of PySimpleGUI but disappeared as persistent windows became the primary use.
To make a single line, one-shot-GUI, you combine the layout into the call to Window itself. You also "chain" the call to read onto the end of your Window call.
The result is a line that looks like this:
event, values = sg.Window('My single-line GUI!',
[[sg.Text('My one-shot window.')],
[sg.InputText(key='-IN-')],
[sg.Submit(), sg.Cancel()]]).read(close=True)
You can take this approach one step further and parse out the input value directly into your variable by adding more code onto the end of the line. In this case, a subscript to pick up the second location in the tuple that's returned from read and then the key.