> Python might not be the right choice for an embedded platform.

I use micropython in several of my projects for CPUs that are waaaay less powered than the thing they're putting in the Librem5 and, despite not being a 100% feature full implementation of python, it's still a very capable platform. Granted, I don't drive any UIs (yet), but those components would be handled by some native libraries anyways on the Librem5, and the choice of python vs C would not matter from that respect.

But it's not micropyhon, you have many apps running on a phone and want them to be as efficient as possible.

From my experience with Vala (compiles to C) it would have been a much better choice.

GTK is re-writing bits in Rust, so it’s a pretty robust option overall. Lots of work left to do!

I only dabbled with Gtk-rs for a bit, and Rust does not really fit my UI/UX workflows, but I would still suggest as major improvement a better way to being able to reference struct fields from callbacks without the current Option<Rc<>> workarounds.

There are already some projects that let you do that, consider Relm for example: https://github.com/antoyo/relm/blob/master/examples/http/src...

Is Qt with Rust usable already, or it's still very experimental?

I don't have personal experience, but my understanding is that GTK is much easier since it's in C; QT makes use of some C++ features like inheritance that don't have a direct analogue in Rust that makes it hard. I've heard of several people doing things, but am not sure there's a particular go-to amazing solution at the moment.

The last time I looked into it, there was this project: https://phabricator.kde.org/source/rust-qt-binding-generator...

But it was in the prototype stage then.