I really have very little knowledge about Linux.
Neither I ported anything, just cross-compiled code using arm-linux-gnueabi toolchain, but modifying little to nothing.
I've drop a lot of hours over it, definitely not my place.
Graphics stack? Toolchain? As far as I know there's nothing official, allwinner drivers are usually non-existent, as well as their support.
I doubt hantek is using the graphics hardware, it seems it's a plain frame buffer, and all the work is done by the CPU.
It doesn't even support double buffering, so I'm 99.9% sure.
I've played with few graphics libraries in this thing...
LVGL seems to be the fastest. I just ran some demos.
And that already required a lot of time because the documentation was obsolete, so the variables, functions, were named differently. Argg the Linux thing...