What are the advantages of SM3 and SM4 compared to NIST-approved algorithms (SHA3 and AES)
If you are seeking a government contract with China, you might be required to use Chinese government standards for cryptography, just like if you are seeking a government contract with the United States, you might be required to use United States government standards for cryptography.  There are many national pride cryptography standards that have little technical reason to recommend over widely used systems like BLAKE2, Ed25519, etc.  Some of them become prominent enough to matter commercially.