That's an interesting project. Rewriting for Onyx could be feasible:
The only file that depends on the Pocketbook SDK is ./client/ui.c. It includes the <inkview> library and uses the following functions: SoftUpdate(), ClearScreen(), SetFont(), DrawString(), FillArea(), DrawRect(), StringWidth() (cf.
http://donkey.vernier.se/~yann/pbapi...nkview_8h.html)
Unfortunately, there are no direct analogues of these functions in the Onyx SDK. And you have to take into consideration that Onyx uses C++ while Pocketbook uses C...