You're linking to Google Play's documentation, not Android code itself that GrapheneOS etc. are built upon

You can find hardware identifiers exposed by Linux distributions more than by Android itself. That Google adds a nice sauce on top... yeah that's a sorry state of affairs, but an optional layer if you don't use the stock OS if it ships with Google Play

edit: but I appreciate looking it up nonetheless! I wasn't completely sure that I hadn't missed that Android (AOSP) includes this now as well