That begs the question, what's the difference between S905D2/X2 and S922!
HDMI 2.1 support will be a big difference if it makes it into those two chipsets, but then new displays & audio equiptment will also need to be purchased as well.
I'm not sure what "AVS2-P2" is, it could be hardware decode support of the upcoming AV1 video compression format.
AMLogic are part of the Alliance for Open Media, who are developing the new Open Sourced AV1 video compression format.