There’s a community for RSS here on Lemmy that has really great stuff, and I found RSSHub on there. RSSHub has both a wiki of how it can be used for things like major social media platforms, and also has an extension for quickly pulling RSS URLs from things like WordPress blogs 🙂
Probably you want lemmy community unique rss suggestions but I came across this similar question on tildes and was reminded of this question so I’ll just leave it here:
https://tildes.net/~tech/pym/recommended_rss_feeds_readers
https://tildes.net/~talk/pom/what_blogs_newsletters_do_you_subscribe_to_and_why
It not necessarily need to be lemmy centered, but I’m interested in content that is worth reading when that notification pops up. Sometimes we find some obscure and interesting sources that “I wish I found it earlier”.