It's always the same problem with these chips. Documentation.
I guess? there must be some IP issue reason behind not disclosing anything about the USB3, Ethernet and SerDes peripherals. That bites.
Oddly, chinese companies don't seem to care much about IP in general when it comes to others' IP, but they seem to be pretty secretive about their own. Yeah. Something I've noticed numerous times.
But in this particular case, it may come from the fact that those peripherals are IPs they bought and for which they are not allowed to disclose any details to their customers (otherwise licensing might have cost them much higher.) Again, just a wild guess.
In any case, if the only way to use the chips is using binary blobs, no thanks.