reference: https://en.wikipedia.org/wiki/List_of_platform-independent_GUI_libraries
QT
language: C++, QML and Python (language bindings)
Platforms
- Linux (X11, Wayland)
- OS/2
- macOS
- iOS
- Android
- Microsoft Windows
- WebAssembly (partial)
GTK
language: language bindings
no android support
Looks a bit alien outside of gnome
Platforms
- Linux (X11, Wayland)
- Microsoft Windows
- macOS
- HTML5
Iced
language: rust
Platforms
desktop
Flutter [notes]
language: dart
Great documentation
Platforms
- Windows
- macOS
- Linux
- iOS
- Android
- Web
For running on Raspberry Pi there is flutter-pi
Kivy
language: python
Focused on multi-touch applications
Platforms
- Linux
- Windows
- macOS
- Android
- iOS