Unable to answer "Are pedestrians forbidden to walk on this road without sidewalk here?" – Sundstabacken (Minor/Unclassified Road) – https://osm.org/way/779320931 via StreetComplete 58.0:

Inget förbud, men det finns ingen trottoar på den sidan.

Attached photo(s):
https://westnordost.de/p/216750.jpg