FYI:
S905X4 (SC2) maybe do have a locked hardware video decoder and therefor it can not be used without the necessary TDK/SDKs by signing NDA. As CE is a open-source community this might happen never. We got the device booting and Kodi GUI shows up and sound works normally. This is current status we have and the development is on hold now until we can find more information.
Status by 11/2021 if you want to use CE on the device: