Swipe to mark as read
On mobile/touch devices, it would be more convenient to be able to swipe articles in the list to mark them as read. The elementary notifications indicator has a nice-feeling implementation of this in GTK, though it's GTK3/LibHandy and not GTK4/LibAdwaita.
https://blog.elementary.io/multitouch-gestures-in-elementary-os-6/#other
This could also be nicely paired with #103, where swiping one direction could mark as read, and swiping the other could archive.