An app that is open source and can extract the page content in a simplified “Reader Mode”.
Anyone else remember Google Reader? Not OP’s question, I know, but holy shit was Google Reader good times.
Feedbin. Not a Linux app, but a web app. And not FOSS or self hosted. Just a really great app run by great people for a great price. Parses full content and has a pretty nice API.
Emacs
Can’t go wrong with Fluent Reader. It’s beautiful and featureful, has a reader mode as well.