That said, I don't know how much the gold price is affected by gold ETF vs physical transactions.
[1] example of gold coins that are very popular with easy liquidity: https://catalog.usmint.gov/coins/precious-metal-coins/gold/
[2] example of liquidity via ebay sales: https://www.ebay.com/sch/i.html?_from=R40&_nkw=gold+eagle+co...
[0] https://www.royalmint.com/invest/bullion/discover-bullion/ca...
It all went well for him until he started a payroll company to do the same thing in multiple states.
https://www.fff.org/2013/12/09/the-u-s-vs-robert-kahre-a-hor...
That said, I'm mainly playing with a hypothetical here. I'm highly skeptical the system will outright fail simply because the majority of the wealth (and thus power) belongs to those with a deeply vested interest in not letting it fail and there's generally not much power owned by those who actively want it to fail. Fiat has worked this long, so why not longer?
When the chairman of the Federal Reserve becomes a prepper, then you know it's time to find a shelter.
For total meltdown SHTF scenarios soap, alcohol, cigarettes, chocolate, and maybe seeds are much more practical as barter currencies.
Even without SHTF scenarios, physical gold is a poor store of value because selling physical gold to a broker is an expensive business.
A lot of prestige gold coins are sold at a price premium which brokers will just ignore when buying from you. Even on weight alone, you're very unlikely to get anything close to your purchase price unless the price has gone up by at least a double figure percentage.
The real question is how bad the Covid recession/depression is likely to get. If you're assuming there's a depression-scale downturn then "paper" gold makes more sense than a lot of other investment classes.
There are many, many scenarios other than Business-as-usual and Mad Max. Look at how hyperinflation has played out historically. In Argentina in 2001, imported things like medicine became very expensive. People sold small amounts of gold for fiat when these kinds of expenses came up.