I adore this app and it makes it even more fun to wander around new areas on foot.
One thing I ran into is that there are buildings that aren't shown in Street Complete. I tried adding a note but there seems like no way to add them in. If there was some easy way to flag a property as having a new building and relying on desktop users to fill in the details that would be super helpful!
But shops can be added (using shop overlay).
(I am one of people developing StreetComplete)