Almost exactly the same size as the island of Great Britain, and while distanced somewhat as the crow flies, precisely one (1) plane fight away from many places.

Hmm... Remote, yes, but wouldn't describe it as a small island. It's actually a collection of island, of a similar land mass to Great Britain or Japan.

But yes, being remote, and being islands surrounded by lots of ocean definitely helps.

NZ is not a single island :)

Also, both of our largest islands are far larger than Czechia. The South Island/Te Waipounamu is over twice the size of Czechia.

Ok, but the core issue you're intentionally ignoring is that nobody wanders into New Zealand without being vetted by border control. Except for a couple of oddballs who boat in (to a couple specific ports) every single person comes through an international import.

The core issue you and everyone else who makes this islands arguement is intentionally ignoring is that no country has been flooded with covid spreaders through a practical inability to enforce its borders. That Czechia or anywhere else doesn't only have people coming in through a couple specific locations is a policy decision. They could effectively be an island if they wanted to.

The US has tried and failed for 80 years to close its southern border.

Unless you're suggesting the US station ten million soldiers on the border and shoot anyone who tries to enter (hint: this is not politically feasible) closing the US is hopeless.

How much Covid came from Mexico, and not through the airports? The Mexican border is a trojan horse in this discussion.

It doesn't matter "how much" came through. If even a handful of cases come through the border, and you have no internal restrictions, it's exponential spread. You either have 100% hard borders, or there's no point.

Sure, it's definitely easier to enter Czechia illegally than NZ.

...so how much Covid was brought to Czechia by illegal entry?