It is a little more complex than that. You cannot only consider how big is a country or how big is its grid.
If the Europe would be hit by a solar storm, assuming that not all of it was hit we can recover the grid in about a month and the blackout would not be longer than maybe a week.

But a solar storm would destroy also everything else, so how big is the grid is really irrelevant when you basically have every other piece (excluded the few hardened enough) destroyed.

Any country with competent leadership could have squashed the zombies in a couple months.

True but you underestimate people stupidity.

After experiencing the covid-19 outbreak I am now fully convinced that a zombie apocalypse is feasible, there would be people denying the existence of the zombie virus, just going to the infected an getting bitten because they wanted a pizza or something, that and people just drenching themselves in bleach or something because they heard that keep the zombies away from some dude online. Stuff like that.

Isn't that the case in the 28 X later series? Like England fell to a zombie apocalypse but the rest of the world is doing fine?

Not sure, though, how this ploy would work out for our fine fellows in South America and Canada, the ones currently belabored with being the closest neighbours...

Fuck Mexico, I guess.

Just uhhh... Build a wall, I guess?

If the country has a bilateral tax agreement with the US and your income is not high by middle-class standards, you can deduct the foreign tax from the US tax. Foreign tax is typically higher if you're anywhere in Europe of the developed world (leaving out the Gulf countries and Saudi Arabia). You still have to file in the US, which is an inconvenience and an expense, but you're unlikely to be double-taxed.

You won’t have to pay anything unless you’re pulling in the equivalent of >$126,500 USD in foreign income. Then you’re taxed on what you make above that. My H&R Block lady here in Germany told me all about it when I file every year. And boy howdy is fuuuuucking stupid that I’m having to file US taxes every year. I could stop, but then everything falls apart for me.

I would get a case of beer and go to the library and read until the internet was back on. You can't stop my escapism that easily.

We could party like it's 1899!

Or instead go bonkers as society devolves:

The Carrington Event

That's known as a grid tie system and my edit mentions that. The only way it's going to help is if the grid is physically disconnected from the building as in the wire is not connected to the building at any point.

That wouldn't be an off grid building then.

A hundred years ago most food was grown a days walk away from a person. With no Diesel production or distribution, which some flairs knock out, there is no warehouse refrigeration.

Even with reserves, there are spare parts drying up. Trucks, ships and planes need constant work.

Some areas would get by, grains and beans can be moved without all that. Probably a huge percentage would survive. Barely

the Faraday is enough for any solar flare

Faraday cages are useful. But CMEs are not solar flares. They are very different (though sometimes loosely correlated) phenomena.

During the recent Iberian Peninsula Blackout, which in practice meant a whole day without power and most of it without water, thanks to a past phase of mine as a bit of a prepper I:

• Had a windup radio which I used to keep up with what was going on and some entertainment. It also works as a flashlight, so covered that side also.
• Quickly concluded that the water supply of the city I live in was likely to get compromised because the pumps are powered from mains so the first thing I did when I got home was fill a bunch of containers with water, most of which I ended up using. Also I already had 10L of drinking water stored just in case.
• Had some freeze dried food so wasn't worried about running out of food (though 1 day is nowehere near enough to empty normal food reserves if you keep a few cans of food around, so I never got close to having to use it).
• My habbit of having some cash with me meant I could buy a bit of extra food from a local grocer which was open at the start of the blackout. If you pay everything electronically, you're not only screwed in situation were mains power goes down but you're even vulnerable to the consequences of banks having problems with their systems (which happens once in a while)

Anyway, my point is not to go full prepper, my point is that some elements of that minset and practices will cover the far more common kind of problems - which happen maybe once every few years - that leave you without power and water for a few days.

One thing I did find out is that I probably need something like a solar powered powerbank for loading my tablet since that's how I mostly read books nowadays (didn't actually need one in this blackout as it was of just a day and as it was offline the charge was more than enough for it), so I've ordered one.

Little things like that mean you don't actually get unecessary stress in a situation like this.

It's not something that is going to save you from nuclear holocaust or in general the collapse of human civilization, but it will save you from spending days without food or water or the stress of not knowing what's going on, such as in such a long and unsual blackout, a flood or other similar more frequent catastrophes.