If it was produced by a Chinese factory it would have a Chinese factory stamp instead of a German one, over 1 million unlicensed copies of Gewehr 88 were made at the Hangyang Arsenal near Wuhan between 1895-1944, so there were a lot of Chinese receivers to be found, while the M1 carbine was never produced by the Chinese Arsenal (licensed or unlicensed) and only 361 units were known to have been supplied to the Chinese forces during WW2 by the US, It wasn't until 1966 did the US supplied the exiled Chinese or KMT army in Taiwan with more M1 carbines. production of Gewehr 88 ended in 1899 and production of M1 carbine did not start in the US until 1942, that is a 43 years gap in between the 2 designs, so the likelihood of this rifle came off a an actual production line is nil.
It is a fascinating sample for sure, but without a background story on this particular rifle or other surviving samples, most likely it is just a surplus Gewehr 88 action rechambered and fitted to a M1 carbine stock someone have cobbled together, where, when, and by who is the BIG question.