Create Flask Project in Pycharm. File -> New Project -> Flask
Add variable for inspection in app.py line 8. E.G. x = 5
Set Breakpoint in app.py in Line 9.
Click Debug Button or Press Shift + F9.
Click the link to http://127.0.0.1:5000/ that appears in the Console.
Enjoy inspecting!

inspection-2
click to enlarge