We are attempting to replace a Map Series StoryMap. The Portfolio app checks a lot of boxes, but one major functionality missing is the option to have your current map extent persist across multiple sections. That is, if you zoom in to an area of interest on one tab or section, then switch to another section, the map would automatically zoom to the same area.
I know this functionality is available in Experience Builder using Map Actions (and we may end up going with ExB on this project for that reason). However, it was a great option in the Map Series template, and I think adding it to Portfolio could expand the use of Portfolio as a replacement for Map Series StoryMaps.