As I started to use static site generators like Jekyll and Gatsby, I started to wonder why Drupal couldn't also be used as a static site generator. After a ton of work, more than any on any Drupal module I've made, I created Tome, a static site generator for Drupal 8 that stored content, config, files, and HTML statically.
There's a lot to say about Tome, but it may be better to read the blog post than to put a big summary here. Needless to say, it works, and the site you're viewing right now is built with it!
Project page: https://www.drupal.org/project/tome
Website (made with Tome!): http://tome.fyi/