Not a wide in the number of sources (yet), but I'm curating a directory/reader/search engine of personal blogs, and the "Global" view shows the latest posts across 1300+ feeds: https://minifeed.net/global
[1] https://philippdubach.com/standalone/rss-tinder/ [2] https://news.ycombinator.com/item?id=46602227
Either way I was thinking to implement those.