Yes in case of currency crisis we enter hyperinflation and government can’t service liabilities in gold.
The case against SGB is it’s purely a govt guarantee not even backed by gold. Some mutual funds are also backed by gold eg. SPDR gold fund in US. But again all of these there is no physical delivery.
Digital gold , yes government theycan also ban it but since there is no lock-in (unlike SGB) we can get it out in early situations if such situation is developing.
Also not sure if a service like Augmont diversifies it’s political risk by keeping physical gold in multiple countries as govt in Britain as well as US has refused to service gold obligation to public in past so it’s a known risk to gold industry.