I think the multi-fuel motors in question are built by Raider Outboards, and appear to be based heavily on the old OMC 35-hp 2-cycle motors from the 1990s and earlier. Sometimes simple beats high-tech. Given the massive amount of small engine manufacturing already done in China, it’s hard to believe that they don’t have a clone of this design running... especially given OMC’s global reach at its peak (before the Japanese brands took over).