Actually, IIRC (and correct me if I'm wrong) for accounting purposes, gold counts as "cash & cash equivalents", so if it bought $1B in gold bars, AirBnB's cash wouldn't change.
Bonds can be considered cash equivalents if they have short maturity.
Gold is highly liquid, and from what I've read, it can be considered (in bullion) cash equivalents, except for banks, that due to Base 3 regulations can only consider part of their gold holdings as cash equivalent for liquidity purposes.