The fine folks at Buttondown made a tool to combine multiple RSS feeds into a single feed. I don’t currently have a use for this, but I think it’s a neat idea.
@bradbarrish I use folders in my rss apps .. that kind of solves the problem but what I really want is to filter post by post … kind of why I don’t like genres in music .. the genre will vary track by track … let alone album by album and certainly not artist by artist .. so as I think through the downside of what I want I become very happy with what I have.