There’s a second C++/QT tray icon wrapper that’s actively maintained by @Martchus. In principle I think it would make sense to add a QT wrapper to the existing windows, mac and gtk wrappers. However in my opinion the main reasons is to simplify the interaction with Syncthing and make it feel more native. QSyncthingTray doesn’t bundle Syncthing, so it doesn’t simplify the installation.
It works by itself right now. There are a couple of minor usability errors about it, like the “check for updates” always report new updates when there aren’t, or the default syncthing path not being the correct one. But these are unnoticeable on daily use.
In Linux that doesn’t matter, as all packages are aware of their dependencies.
Actually that’s a more desirable scenario, as you can easily use and test different versions of syncthing with it.