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).
If you snickered, take a look at this project of mine that unifies manpages, apropos, cheatsheets, and TLDR sheets.
If you use TMUX, you probably want to take a quick look at this post. 🙂
Two very nice QoL tweaks to my script that automatically creates diverse playlists for MPD.