Certain feeds like those from Quanta do provide almost the full content you get from the article itself on their site.

https://api.quantamagazine.org/feed/

You get pretty much all the content (sadly missing the incredible images).

Other public information, like that from Science Mag, has almost nothing but headlines (at least from the ones I've reviewed).

https://www.sciencemag.org/about/email-alerts-and-rss-feeds

I'm reading things from ScienceMag and having trouble retaining it, so I want to track information as anki cards, but they don't really provide the information there other than a headline and a summary.

What RSS feeds are out there that contain "good and complete content" and don't require you to head over to their site to read the entirety?

I can understand why a commercial service would only provide headlines as a teaser, but surely there are good publicly produced RSS feeds that have rich information (and want to syndicate it as widely as possible)?