It sounds simple on the surface. You copy a link on a site into a feed reader app. Then whenever that site updates you get a nice readable article on the app.
But that sounds like something that could be accomplished locally. Why does every RSS reader I run into require an account or otherwise rely on the cloud?
You can use ones that don’t require an account or any cloud whatsoever. Check feeder (they also are on the play store) on android, and akregator for linux/windows.