An economy based on bitcoin would have extreme incentive to keep electricity and internet on all the time, and fix it quickly if something happens. All the more reason to want bitcoin adoption world wide. The more that incentive spreads the better it is for humanity.

it's a good question and an interesting problem.

you will always need computers to sign, send and verify transactions. but these operations are lightweight such that you don't need much power. all of the above can be accomplished via something as simple as a raspberry pi connected to a solar array.

the real challenge IMO is robust, censorship resistant bandwidth. bootstrapping a node requires downloading and verifying the entire ~500gb chain. you can trust someone else's node, but this may not be wise in an adversarial environment (and in bitcoin land we do like our "worst case scenario" thought experiments). it's even trickier when talking about lightning as nodes must be online to receive payments.

My emergency and bug out kits contain food, water/water purification, first aid, compass and analog maps, cash, ammo, plus silver coins and some amount of gold. However, I also have barter networks I already nurture. If shit hits the fan I may have to adapt, but I will not have to start new from some lost, useless situation

If the power is out for long enough, I think you won't be able to pay with cash, too. Stores need power for all kinds of things like registers, lighting and refrigerators. I imagine they would close pretty early if not immediately.

Additionally, long-term power outages are emergency situations if you live in a region that depends a lot on power. There will be looting. You won't think about your bitcoin in such a situation¹. You will care about food, shelter and being safe from your biggest threat: other humans in survival mode.