Very simply, this is a document viewer type version that plays a similar role as mailcap and other such utilities. Its focus is on displaying documents quickly in a terminal (or a popup terminal).
Here’s a quick feature/overview of the programs I’ve written that I’m happiest with.
Enhanced, modular, bookmarking for newsboat, newsbeuter, or (for that matter) anything that can pass a title and an URL to a program.
If you snickered, take a look at this project of mine that unifies manpages, apropos, cheatsheets, and TLDR sheets.