It’s all verifiable. We haven’t revalued US gold reserves since 1973. If gold were worth, say, $8k/oz, and were revalued from the current $42/oz set in 1973, that would instantly add almost 2 trillion on paper to US reserves. All it’s doing is acknowledging the current market price for accounting purposes.

FDR used a similar trick to devalue the dollar, allowing him to expand the money supply. Of course this was when the value of the dollar depended on the value of gold, so the motivation and the effects were different.