When you said "GUI Programming" What kind of GUI are you talking about? A web-based GUI or a desktop-based GUI?
Web-based the go to framework is generally React or Angular.
If you're talking about Desktop based, you probably want to stick with the language that you're also building the logic in. Like you could use another language like C# and write a front-end in Avalonia, but then you'd have to interlop from C# to Python.
You could also pick a language that's supported by Electron, then you'd basically be doing Web-Development but for desktop.
Well "Device based" is even more broad, haha. If you're also including iOS and Android.
Then you'd be looking at a cross-platform developing lanuage, like Flutter, React Native, Xamarin etc.
So the question is, what is the goal for your GUI? Is this a personal project where you just want to have a GUI for a specific system? (Windows / iOS system) - Or something published that you want people to be able to use on all devices?