How to record HDR: Choosing HLG or S-Log gamma curves in your camcorder

Hello Alvaro,
thank you for you content, you described it very well, there are just a few videos out there, who explain HLG on Sony correctly.
I Have a question where i can´t find any information on the internet, maybe you can help me:

I film with the a6600, with HLG 2 and BT.2020, I am really happy with the results on a HDR\HLG TV.
But, instead of your Z90 which saves the file in 10-bit, my a6600 saves the file in "just" 8-bit and I have difficulty to understand why I can choose these option, when it is "theoretically" not possible.
Includes the 8-bit file like "real" BT.2020 color combinations and brightness information like the 10-bit range?
There are a lot of forums who just describe it as ""Sony´s fake HDR" but maybe you can explain what it is really about.

Thank you very much,
Felix