And even if you want to keep it non-web, I don't see why you'd use gtk instead of qt (especially since QT has pyside6). And I'm not saying that as someone who likes QT either. I wish I started my PoC with web tech from the get go actually. But still, it's so much more convenient and even if you stick with c++ QT still provides a lot of nice to have tools (for threading, signals, concurrency etc).
I haven't used qml a lot but I wonder if gtk has an equivalent to that too. What am I missing about gtk here? Like, where does GTK beat qt?
C API is the big one. Unless your language is officially supported by Qt (meaning C++ or Python) you're basically screwed.
Secondly would be the license, while they're both LGPL these days, that wasn't always the case, and the current Qt company is highly hostile to open source.
I haven't used qml a lot but I wonder if gtk has an equivalent to that too. What am I missing about gtk here? Like, where does GTK beat qt?