As to what you said before, you are correct, there is technically no way to write a webpage with Python.
The reason why is because webpages can (basically, I'm oversimplifying here) only be made with HTML (to define the content), CSS (to define the style), and JS (to make it interactive).
You could write Python code that could display a webpage (or, rather, host it) and then you could see it appear in your browser, but in the end, that webpage is still HTML.
Can Python be used to write an Android/iOS app? Well, that one I'm not too sure about. You might technically be able to, but you'd have to figure out how to compile it into something the mobile devices can understand, and there is no existing tool (that I'm aware of) for doing this at the time.
Python wouldn't really be the best language for that anyway.