You could get started with Qt, specifically the legacy widgets. There are bindings for Python available (pyside or pyqt) if you don’t want to learn C++ or another language right away. You can also port your GUI definitions to other languages at a later date.
Arch on desktop/laptop because I’m very comfortable with it, and I can set it up the way I like.
Debian on servers because it’s stable and nearly everything has a package available, or at least instructions for building.
Same as OP, but I’m not likely to change them out. I’ve tried a lot of distros over the years and this is what works best for me.