Not sure exactly what it has to do with gnome or dbus, the desktop is backed by X11 (Migration to Wayland is underway but it's a pain to work with), the Flutter embedder itself renders with GTK. The project was started as a Fuchsia fork, and we intend to continue working hard on getting that ready, but sadly a lack of access to compatible modern hardware forced our hand to temporarily switch over to Linux as the development platform, so our layers of project would not stagnate while we wait for more polishing on Google's end.