SomeoneElse
Just for info, some of these are mapped as "information=route_marker" to the south - see https://www.openstreetmap.org/node/3778603684 for an example.  I'm not sure if that's the best tagging - definitely open to suggestions.  They're also added to the relevant relation, in this case https://www.openstreetmap.org/relation/919241 , and that does show up on maps that show walking routes.