I think koreader[0] has an RSS feature where you can fill in some RSS feeds and it converts feed items to epubs. It's nice, but I'm using a different reader on my laptop, so then syncing (of which feeds you follow) becomes a thing to do.
Instead of following a bunch of them and having to sync them I guess you could just follow the combined one and be done with it. If you have multiple feed readers, each with their own way to input feeds, I think something like rsscombine might be an easy solution.