In order for a cryptocurrency to be the solution to that problem - an authoritarian government routinely destabilizing a currency, or freezing financial account

In order for a cryptocurrency to be the solution to that problem - an authoritarian government routinely destabilizing a currency, or freezing financial accounts - that cryptocurrency would have to be ubiquitously in use by everyone involved in any financial interaction. Grocery stores, clothing outlet malls, lawyers, healthcare services, rent/mortgage services, etc. would all have to be on-board with using that cryptocurrency and have the infrastructure to facilitate it. If they didn't, you might as well have a frozen bank account, or a hyper inflated currency. If you're in a state that can freeze bank accounts and completely retool the national currency on a whim, what prevents them from strong-arming every one of those above-mentioned institutions into not accepting that cryptocurrency? If you can freeze everyone's bank account, you can certainly enforce jail time for a store owner who is found to be doing transactions in whatever cryptocurrency. Basically, for cryptocurrency to solve the problem you describe, it would have to become the same structure that caused/causes the problem to begin with. You'd be back to square one.