It's a "real road" in the senses of: it physically exists, and it's not private property.

On some city maps, it's shown with the name, as for example: Parcel map (https://somervillema-live.s3.us-east-1.amazonaws.com/s3fs-public/storage/assessing/parcel-tax-map-020.pdf); Zoning map (https://www.somervillezoning.com/wp-content/uploads/sites/2/2022/07/Zoning-Atlas-07192022.pdf); a random Paving Detour map (https://voice.somervillema.gov/4794/widgets/16025/documents/31511)

When you get into "the city's listing of streets", that's a rabbit hole into the different types of public ways under MA law.

Since the roadway is narrow, and mostly leads to back entrances, it could be considered an "alley" in OSM parlance, I think.