I recently built something with PyQt bindings and it works really well:

https://gitlab.com/djsumdog/mpvbuddy

In my previous job I wrote a couple of not-too-complicated apps targeting Linux in PyGTK and I found it to be pretty pleasant, except when it came to custom styling.... mainly because the styling language does didn’t seem well documented and i found it to be somewhat arcane. Didn’t stop me though and the project got done. I wouldn’t mind working with it again