Joseph Weydemeyer was a Prussian officer who was a friend of Marx. He served in the American Civil War and kept a correspondence with Marx. He and his son Otto helped create the first english translations and american printings of much of Marx and Engel's works. Otto actually would become a labor organizer in Pittsburgh and help destroy the first Marxist party here, the workingmens party, because it literally right away went lib electoralism and ignored their base of German and Bohemian only speakers in PA and NJ. https://archive.org/details/HistoryWorkingmensPartyUS/page/n17/mode/2up?q=pittsburgh great book on the matter by iirc the nephew of Eric Foner.

But yeah I think Joseph is the best bet, and the book covers a lot of those earliest figures and orgs