This is a silly idea. There are two obvious ways to "back" a currency; backing it with "specie", or in other words some sort of commodity, and backing it with the power and reputation of the issuer, in the case of the dollar, the "full faith and credit of the U,S.".

In a modern global economy specie is simply unworkable. Commodities regularly vary in price according to the laws of supply and demand, and currency needs to be as steady and predictable in purchasing power as possible so that buyers will trade it in confidence that they won't lose future value in the case of a deflating currency and sellers won't lose value when they accept an inflating currency.

Further, the issuer of a specie backed currency needs to control the bulk of the supply of the commodity in question so that an outside actor can't attack the value of that currency by cornering or dumping the commodity.

For the reserve currency like the dollar, the sheer amount of specie necessary to back the trillions necessary to serve all dollar transactions is daunting, basically not possible to purchase and too expensive to hold.

The full faith and credit of the U,S, government is held solely by that government, who also control the entire money supply, which gives the government control of both sides of the supply/demand equation and thus close control of the exchange value of the dollar. Cryptos have given a full demonstration of the inevitable volatility of a "currency" designed to be deflationary, and volatility is poison to currencies.