Can you be more specific? Which UI? Which library? A pop-up for what?
Python is a interpreter-language, so it’s not something generally used to create executable files, but code that is executed at runtime via the interpreter. I’ve heard of a library like “Python compiler” but no idea how it works.
That refers back to 2. - that’s not the usual purpose for Python. But installing something is quite the intricate process with the operating-system, so I imagine you need a bunch of libraries.
It is possible to do GUI in Python, but you need something like Tkinter or wxPython to do GUI programming in Python.
If you don’t know Python already, it will be a steeper learning curve. There are also frameworks like Kivy that are cross platform, but again, if you don’t already know or are not familiar with Python, it will just add another layer and slow your learning.
Languages like Python, Perl, PHP, JavaScript, etc are all interpreted (scripting) languages, not compiled. Generally no portable executables. Although there are tools out there like Compile Python To Exe but that is beyond the scope of my knowledge.
There are also things like the links on this page… Portable Python although.
But again, I would focus on learning the language first.
For point 1, you could use any GUI library available in Python, but I would recommend PySimpleGUI, it simplifies Tkinter, etc syntax a bit and is pretty easy to get going with (especially as a beginner).