And if it has a 12-volt input, there's a good chance that can work directly from a panel between about 9 and 15, possibly even up to 20 volts. Don't quote me on that - this isn't sound engineering advice, just an idea of something that might work. If it's a 5-volt input then it probably needs a pretty accurate 5 volts. Same for NUCs and so on (again don't quote me).

You can even use a (right-sized) lead-acid battery without a charge controller, as they're pretty resilient, unlike lithium-based batteries. This will both store power for night and stabilize the voltage. The lifetime would be a bit shorter. You can literally just parallel your solar panel, battery, and whatever you want to power, and it has a pretty good chance of working.

It isn't about the price.

Try to avoid understanding this difficulty from your own shoes, but rather from the shoes of communities very limited on what is reachable to them from a technical, financial and logistical point of view.

I know you can solve it easily. I can solve it even more easily myself.

Now see any disaster area, see any remote area. Setting up Wi-Fi is invariably never a priority for those in such situations. Even as things settle, it is still more practical to share files directly with each other.

When you see from that perspective then you are on the domain of realistic solutions rather than keyboard level on virtual forum.