StreetComplete uses OSM’s built-in note system to leave the notes, so basically any OSM user can see them and react to them.
I use Vespucci now and them, but most of the time I find it too fiddly to use on the go. What I usually do is also have OsmAnd open and use its own note system to make a local audio or photo note. And when I’m home I go through the list of notes and change the things in ID or JOSM.
Has anyone use Google’s zx and can say something about it?