As far as the US is concerned, even assuming the Fed is telling us the truth (serious doubt there), $300 billion in gold reserves isn't of any serious value. That doesn't cover 1/6 of this year's admitted deficit. Forget the total debt.
I was just reading about the UKs gold debacle. How Gorden Brown thought it would a great move to sell a big portion of it’s gold reserves about 10 years ago when it was at a
major low.. Their government is trying to hide the number but it cost them billions in losses compared what it would be worth today . And given the massive inflation coming to that country and what could be the worst recession in decades, they now have almost no gold reserves to fall back on.