Unable to answer "What’s the identification number here?" – Fire Hydrant – https://osm.org/node/10727260625 via StreetComplete 56.1:

Borne incendie

Attached photo(s):
https://westnordost.de/p/200201.jpg
https://westnordost.de/p/200202.jpg
https://westnordost.de/p/200203.jpg