As you may already know, Python is one of the hottest programming language out there, with thousand of job offerings, so makes sense, at least for me, to push this language as official one for GNOME Mobile applications.
elementary OS is doing a good job on engagement new developers, while use Vala as its official language. For me, Vala is a good candidate for advanced/performance constrained Mobile applications.
Both languages uses GNOME’s technologies, through GObject Introspection. So, any new widget designed for responsive Mobile applications, will be available to Python and Vala.
An old License issue on GLib’s static linking on Android, can be tackled by Purism, in a form of tools to allow a dynamically loaded version. For free software, this is not an issue, but for proprietary one.
Provide a high level programing language, potentially distributed in binary form, could incentive app development.
On Vala side, allowing to develop software in this highly productive GObject focused programing language, can push up games or any performance constrained applications, development offering; while you get all goodness of GObject and C world. Thanks to C, GNOME technologies, are available to many other languages; so, Rust and C++, could find their own way.
This is just for discussion and a proposal to Mobile OSs, using GObject based software.