Think: summary
On your feed screen it simply says:
[x] Updates since last refresh
[y] Unread

Click on the 1st line and it goes to a screen showing all the feeds with the latest read/unread at top
Click on the 2nd line and it goes to a screen just showing unread, with latest at the top

Give option for specific notifications from sites for those folks who like to pay attention to specific updates. That would look like
[x] Updates from Favorite Site

Hope that helps

EDIT; Let's get fun with it
App is open in multiscreen view
App shows number of new feeds or icon of latest updated feed item
Semi gesture to go to just that feed
Full gesture movement to see entire feed list

UX thinking is fun ain't it... guess I need to get a Jolla in hand to help out more than just writing words