StreetComplete is one of my favorite apps. It's like Pokemon Go mixed with Wikipedia because it gamifies contributing to OpenStreetMap, which powers (all?) mainstream opensource maps.

Looking forward to iOS support so more people can use it.

https://streetcomplete.app/

https://www.openstreetmap.org/

For the more experience OSM contributors, there is also a fork called SCEE[1] that adds some extra "quests" and a ton of UI customisability!

[1]: https://wiki.openstreetmap.org/wiki/SCEE

iOS has Every Door[1] and there’s also MapComplete[2] which works as a PWA.

[1]: https://every-door.app [2]: https://mapcomplete.org