Amlogic never licensed the Linux "libmali" libs for the T820 GPU in the S912 boxes and the hack to reuse the Android libs has a perfomance impact that was borderline on older Kodi versions and not really usable with K19 and future K releases. LE avoids that by using the FOSS drivers (which are not compatible with the ancient kernels CE uses) but that's a different can of worms.
Sure. There are lots of people wanting/willing to test but nobody has shown interest in writing a driver. As the FOSS development community around Amlogic chips is miniscule (CE contributing to non-upstream vendor/BSP codebases doesn't really advance FOSS) nothing is moving forwards.