For this to work, you still need an entity in Ukraine to accept bitcoin and owning Ukraine currency.

The same thing with 3th world countries: to be able to rescue your money, you need to find someone who wants to take that risky currency and exchange it to crypto for you and back if you need it.

But as soon as Bitcoin/crypto is so established than there is a big chance that the country/dictator steps in and forbids it.yes that is technically possible (see great Chinese firewall)