Personal RSS feed readers can usually do this sort of thing, but RSS readers aren’t meant to be shared, so you can think of the search engine as a 'curated feed list as a public service'.
I wrote a longer blog post about OpenOrb here: https://raphael.computer/blog/openorb-curated-search-engine/
Show HN: OpenOrb, a curated search engine for Atom and RSS feeds
openorb.idiot.sh