It’s more like 3 really wide pixels.

They’d be expensive to run but it would likely only be for a few days per year.

“Pay for more electricity” might not work very well, if everybody in a region uses resistive heat at the same time. I’m not sure what the solution is… maybe an overprovisioned power grid, cheaper battery tech, or tanks of renewable backup fuel like dimethyl ether?

It is straightforward to run an isolated network with TCP/IP, DNS, and web servers. The hard part would be dealing with software that complains/fails if you’re not using HTTPS.

In general, you would want an offline copy of the entire software stack (e.g. a Gentoo Linux mirror) so you can patch whatever problems you encounter.