How is hardware graphics acceleration implemented in android?

Question

linux

Good day to all.
I have been struggling with a problem for a long time: the Chinese flytouch 2 tablet has debian instead of android. Everything works except for video acceleration: mplayer slows down terribly through framebuffer when playing, for example, .mkv, although android itself plays the same videos perfectly. I connected the galcore kernel module (gpu from vivante) - zero to the mass.
I ran android init (yes, by the way, android itself loads tolerably into chroot, because android init has no limit on the process number, I don’t think it’s true that you can write an article about this separately. It loads, but the system process dies + part does not work sensors + the image is loaded across the screen and cut off), connected to /dev/graphics/fb0, fb1 and galcore devices: fb0 is a regular framebuffer without acceleration, fb1 is loading something somewhere, but nothing is displayed anywhere, galcore is also somewhere something ...
And now, attention, the question is: how is hardware graphics acceleration implemented in android?
Where does the system go and what files does it bind to?
I will be very grateful for the answer!