I don't know how helpful this will be, but...
Some years ago my mother was researching ancestors in Bavaria, and another researcher suggested she send to the local records office (Standesamt, in
German) saying what info she was seeking, enclose a $5 or $10 bill, noting that she was enclosing this to cover copying costs, etc., -- and she received several pages of information, including brothers who had stayed in Germany when ours emigrated, and descendents of theirs who were working on genealogy. She was able to correspond with them, and later visited.
I'm not sure about Prussia/Pomerania, but it might be worth a try?