Using the same tool, I can see that my website loads in 440ms in the Netherlands. The homepage is 140kb, makes 6 requests, leverages caching and http/2 thanks to nginx etc.

Which is great and everything, but for a reader in Texas, that becomes 1.2s thanks to the fact that my site is hosted in London.

As you point out, AMP pages which weigh in at 4MB can be loaded in a seemingly underwhelming time: ~800ms. However, I think the important takeaway from this is that the pages load in ~800ms in two different continents.

The articles I publish on my blog use AMP-HTML. I don't include media or ads at all, just text and fonts. These pages fully load in 200ms.

I conclude that the free CDN offered by Google is, frankly, a very attractive feature.