To substitute for the Coast Guard exam? No. There may be non-approved prep courses, but you would still have to take the Coast Guard exam.
The Coast Guard does not approve courses for one module, they approve for the full exam (all modules) for less than 1,6000 GRT, and for “increase in scope” to go from a near coastal license less than 1,600 GRT to oceans. The Coast Guard does not approve any courses for 1,600 GRT or more, including 3rd Mate.