I know you can switch between all and focus mode at the bottom of the feed list, but I would like to be able to "mix" those modes based upon the feed itself. So some feeds would be all items, but others would be focus mode.
I thought about this and I think what you want is to be able to hide all stories *except* Focus stories in some feeds. I do this too. To do this, thumbs down the publisher and then you will only see focus stories. That also works feed-by-feed.