I definitely had my eyes on slint for quite some time (pretty much since it was announced - I highly value the technical skill of their team) but it's still quite far from the whole QWidget offering. I don't know anything else that is even remotely in the same ballpark - certainly not Tauri or egui for instance. Anything that is GPU based is blacklisted from the get go (including QtQuick) - people who preach gpu based GUI have definitely never tried to have a quick debug feedback loop with an app built using AddressSanitizer where just opening the simplest GL or Vulkan context takes up to 20 seconds on a good day.

Slint is not a replacement for Qt. Slint only provides a tiny fraction of what Qt has to offer https://doc.qt.io/qt-6/modules-cpp.html

Only the GUI part is relevant for this discussion as this is what Qt is know for. Other modules also have different Rust crates equivalent, or are really niche and nobody uses them.

that's really not true. There are thousands of projects using e.g.

QtSerialPort (https://github.com/search?q=include+QSerialPort&type=code)

Qt3D (https://github.com/search?q=include+Qt3D&type=code)

QtWebSockets (https://github.com/search?q=include+Qt3D&type=code)

QtSensors (https://github.com/search?q=include+qtsensors&type=code)

Qt SCXML (https://github.com/search?q=include+qstatemachine&type=code)

etc etc..

Qt's value is as an app framework where you can assume interoperation across the same async runtime and enjoy a cohesive set of APIs for all your app's needs.

Name one of those plenty suitable options rust have to replace something like Qt.

Qt is more than a GUI framework. https://doc.qt.io/qt-6/modules-cpp.html

Sure, but the topic is the GUI or so I thought.