Travel via Bangkok to China

I need to fly from South Africa to China (with work VISA).
I am planning my fights to Guangzhou as follows:
1. OR Tambo (JNB) to Bangkok (Thailand) via Dubai – 8 November 2020 - EMIRATES
2. Bangkok (Thailand) to Guangzhou – 9 November 2020 - CHINA SOUTHERN
Can I book separate tickets from the two carriers? Is this flight itinerary acceptable when entering China?
After complying with the COVID health check regulation and negative Covid test 36 hour prior from departure from Johannesburg.