There are ways to add pictures as the tags of the OSM objects

- https://wiki.openstreetmap.org/wiki/Key:wikimedia_commons

- https://wiki.openstreetmap.org/wiki/Key:panoramax

- https://wiki.openstreetmap.org/wiki/Key:mapillary

Mobile apps can use this data to either give links to them (e.g. CoMaps) or display them in the app (e.g. OsmAnd)