I was hoping for this to work but it doesn't parse the full content. Weirdly also it didn't import correctly the opml file, the folders where there but they didn't have the rss link.
Nextcloud's news reader is pretty good -- but you need to host a Nextcloud instance first :) (Hint: you should, to free yourself from google/icloud or whatever you use)
I tend to use either Newsboat or Elfeed. The first one is command line, the second is Emacs. So they're both text-based. Might not be precisely what you're looking for, but with the right choice of terminal font and easy-on-the-eyes colours, I find it a pleasant reading experience without distraction.
I run it in docker and access from browser. It says it can automatically download the whole article. For me I have to hit download button each time, maybe I missed some configuration.
I recently moved from FreshRSS to Miniflux and the matrix integration is a godsend. Having miniflux automatically send everything to element instead of having a dedicated RSS client is great
Miniflux submit selected articles to Wallabag for later reading. I also use the Newsboat CLI client which can sync with Miniflux installations as an alternative to the web interface it’s comfortable.
I'm a fan of KDEs Akregator. It does a great job as a feed reader and shows the contwnt of an entry in a simplified reader mode. However some feeds jist dont display the full arricle in their feed entries so you'd have to follow a link there. But even thats sth that makes Akregator awesome: you can specify the command thats used to follow a link and most browsers have the option to open a page in reader mode via the commandline. So from what I gathered thia should pretty much do all you want it to and then some.
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.