Sorry, I misread you. I thought you were asking for a city / district map - instead of constituency.
My bad (and ignore my pm).
States that haven't yet covered election results in their Geo-Portals include Hessen, Lower Saxony and Schleswig-Holstein (did not check for the other states yet). The federal portal does also not include election results on city/community level, presumably as community mergers are pretty frequent in Germany and they are anyway having problems keeping their basic data (population etc.) up to date and in sync with the most recent set of communities.
Also, because the feds simply don't actually do any of the actual counting - they have no reason to collate the numbers. Really what you want is a link list to all the
Kreiswahlleiter, who'll be city / district officials.
And what a municipality is and does varies a lot state-by-state, Schleswig-Holstein and Rhineland-Pfalz at the one end still having the ancient tiny municipalities for the most part (worse than France
) but not having them do much anymore, rural Hesse at the other end having mostly huge municipalities that aren't, really, municipal but rather, er, subregional (and with powerless Ortsbeiräte councils for the former municipalities, typically, though some municipalities don't have them.)
And where you got tiny municipalities, their postal votes may be counted in a neighboring larger town.
EDIT: Followed your link. Postal votes not included in municipal results for about half the country (Baden-Württemberg, Brandenburg, Mecklenburg-Vorpommern,
Sachsen, Sachsen-Anhalt, Schleswig-Holstein, Thüringen, Niedersachsen, Rheinland-Pfalz). Still great though, didn't know it existed.