The La Roche Electric Works was a large and successful company that supplied towns and cities in the from northeast United States to the midwest with their electric light systems and the dynamos to run them.
I think the La Roche detachable motor was a serious project that was a proof of concept show piece that illustrated another use for the La Roche batteries and their switches. I have found no reference to commercial production. On the other hand I wonder who saw it and was inspired by it.
It was well documented as it was used on the Schuylkill River in Philadelphia and seen by many reporters.
It was made to reuse the pintels on a regular boat that normally hung the rudder.
An article about the company, but not the outboard, is HERE.