The currently available vendor kernel is the 4.9 kernel. This is the only maintained kernel that has support for the hardware decoder and all the other media features provided by Amlogic SoC(such as HDR).
While using something like the current 5.11 kernel would get us lots of nice driver updates. The mainline 5.x kernels do not have working support for the hardware decoders that are in the Amlogic SoCs. They also don’t support features such as HDR on Amlogic devices.
So in short you would end up with support for a couple extra USB dvb adapters, gpu drivers for the S912, and loose the ability to play most video content. Overall not a good trade at the moment for the majority of users that want to setup a device for media playback.