I could see China using the K-31 as well.Perhaps China, too? Germany was very pro-China in the 1930s.
Chinese might want to have something more powerful than the stocked pistols, with comparable rate of fire. They also might be the 1st to order full-auto carbines, inspiring Japan, USA and Soviet Union in process to take note, that in return will cause British and French to raise eyebrows...
Another thought occurred to me, the K-31 could butterfly the FG-42 ( a shame because I love that gun) but bring about an earlier STG-44 (STG-42?) and maybe even a folding stock variant.