remembered one thing I forgot to reply about, the abruptness of the ending is not unknown and is very much in theme, since reality is often abrupt and being hit by things you don't know and could not have easily predicted. From a literary perspective there are small ties lying around, and lots of details that tie together for thematic purposes.
There's a bunch of people who have mentioned being inspired enough to think up of potential extensions and sequel ideas, and while I already have quite a large picture of everything, it would be cool to adapt them somehow as side stories to make the world feel more expansive too :p