Everything I said in my previous comment, and then some. As the story progressed, there is still more tech, that probably is far fetched (at least at this point), and some that is at least somewhat doable now. It just makes the story that much more believable. With only a tiny bit of suspension of believe. It does lean into the spy thriller aspect a bit more, only the main characters aren't really spies - it's just kind of has that feel to it.

The ending was un-expected given the start of the story.
It is a really good story, and I'll give it 4 out of 5 stars.