To be honest, I'm not the best to ask about Python. I need more rigid languages for my daily job, so it's much quicker for me to just throw down a small project in one of those.
I do know, though, that Python comes with Tkinter out of the box. People usually don't praise that all too much, but it's probably fine for small GUIs.
However, it's almost certainly worse than Powershell/.NET for creating Windows-only GUIs.
If you'd like to write GUIs on the Linux side, then I would frankly recommend not doing that.
No Linux sysadmin wants a GUI to deal with. If you give them a CLI, then they can automate that, i.e. integrate it into yet another (probably Bash) script.
Not to mention that most Linux servers don't even have a graphics stack installed...