Surname Emichen

My Ancestor Johann Ernst Emichen (name recorded by a fellow Palatinate)

This man has been a mystery inasmuch as his name has turned into various forms, once he left Prussia.
In America, it became Emiger, used by one of his sons.
Then it became Empie and further, during the American Revolution, Empey split off from there.

Johann Ernst Emichen has been listed, but not proven, as a son of Johannes Emmerich.

I have read that Emmerich, Emichen, Emig, Empie, Empey, Impey may have all derived from the "Land of Essex" where the name meant "dwellers amid the young trees" or something like that.

I wondered if any databases in Germany had any documentation or knowledge of this family, when they lived in Prussia?

Not sure where to start looking, as the Lutheran Churches of that time period were reportedly burned.

Any clues or bits of information would be well appreciated.

There are Empey lines from Ireland and England that have "brick walls" as I have not been able to connect them to my tree.