But I’m also wondering: if the internet or electricity is down in a war zone, would it be hard to actually use Bitcoin to pay for things?
There are also an alternative solution for this problem. If the internet is down, Bitcoin transaction can be sent via satelite communication, there is also an SMS base transaction together with Mesh Network and Radio Transmission.
[1]About the electricity, the availability of solar-powered batteries and power banks is enough to power a mobile phone or even a computer to send a Bitcoin transaction. With these types of power source, people can still have access to electricity even if the main provider of electricity shut down.