Black markets always exist and you cannot be in business without being in business. You demonstrate what you have for sale (the glass case), not necessarily what you have in the back room or on request. In the various black markets, they have ways of signalling their clientele what is available. If there are not walls around the city, then stuff is available and can be transported, it's just a matter of what it takes to get things moving again.

If for whatever reason, there are refusals to do business, then we would have to determine why and address that. I seriously don't think anybody in Venezuela or even Aleppo right now is refusing payment in bullion. In fact they probably are taking US dollars.

Show me any reasonably priced lunch counter type place that is accepting bitcoin.

The video game "The Division" is pretty well thought out on the scenario end even though level based game play positively sucks, the backstory and scenarios are pretty solid. The Survival guide they have on Amazon is absolutely amazing and very well thought out. I would suggest getting it even if you don't play the game.

One thing they mention in that is food trucks. Some areas have them more than others, but chances are, someone will keep some running and street food vendors are everywhere in one form or another. They often go back and forth between the fast food business and involve many of the same people. For example, successful food Kart operators frequently get corporate offers to manage a fast food joint. Likewise, fast food joint managers often just want to leave the corporate world and want independence to make their own menu and be more connected with the customers so they build and set up a food kart. I have personally seen that scenario plenty of times. Some guy who is just tired of all the headache of running a big joint pays me to build his dream food kart and he spends the next few years servicing his own customers directly. He wants to be the chef at the never ending barbeque and handing off his smoked ribs and chicken off to smiling customers. Another one, a Subway employee was scraping all of her meager savings together and borrowing money from her family to build a custom food truck out of a small school bus. By the time it was getting closer to done, her boss called with a promotion offer. She took the offer and sold the food truck for what she had into it.

I traveled in Central America in the 1980s when there were Communist revolutions going on, and all of the middle class families owned some sort of storefront operation. Even the lower class but aspiring middle class people did. I remember Indigenous people straight from the bush who would set up a roadside stand selling fresh squeeze pineapple juice.

There is also a whole series of meanings from the Spanish phrase and Latin concept of "Plato o Plomo" or "silver or lead". Or shall we say, "the offer which ought not be refused".

In the event of ANY of these world hotspots, there tend to be hotels and services available, although at "white man prices". That is where the commerce happens, and if it comes time to be trading supplies, sell out, close shop and move on, then it's time to do just that.

If you can organize anything, or be part of a larger organization which actually gets stuff accomplished, and it is getting done on terms acceptable to you, then that opens up other options, but lacking more information, I don't see bringing those options to the table.