In case NiLuJe doesn't see this question, FBink is a low level interface to the various quirky Kobo (and even some other) hardware, thereby sparing the rest of us the misery of dealing with same.
Not at the level of Gtk, but a primitive input system was used to create a keyboard in golang built on FBink (it would be nice if you or the dev pushes this further because golang is so friendly)
:
https://www.mobileread.com/forums/sh...0&postcount=14
A more sophisticated toolkit , rmkit, was ported to FBink using C++, including the best puzzle collection and drawing app available on Kobo:
https://www.mobileread.com/forums/sh...86#post4403186
A few apps including a minesweeper game used a python toolkit on FBink:
https://www.mobileread.com/forums/sh...60&postcount=3
There have been other approaches, including chess apps on the browser(html) and Plato(rust) platforms, e.g.a KOReader calculator plugin(lua script), a Qt anki standalone app, only a few of which are linked here:
https://www.mobileread.com/forums/sh...07&postcount=4
If you just want to run your gtk app on your own machine, schuhumi's fbink-xdamage was used by NiMa (eventually inkbox/quill OS) to create an xorg environment on Kobo, which I have run alpine linux gtk apps on:
https://www.mobileread.com/forums/sh...d.php?t=336210