Hi Cedrik,
Regarding community contributions, after someone mentionned LVGL on the PinePhone that got me thinking a bit, trying to guess in what direction the PP GUI will go. (I make no guarantee express or implied that my below ramblings will be relevant to the Genode project, caveat emptor :^)
your question prompted me to summarize the thoughts that went into the mobile UI for the PinePhone [1].
[1] https://genodians.org/nfeske/2023-01-05-mobile-user-interface
The "left" side relies on Genode's native widget renderer (menu_view). The "right" side offers complete freedom. One user may host a single Qt app at a time, another user may host an SDL game, or even host a custom UI mimicking a commodity smartphone experience (launcher + switching between apps). So we can explore different directions without the need to agree on the one best way.
Cheers Norman