Travelling to Hong Kong then taking bullet train to enter China to Guangzhou

Hi,

I hold a Malaysian passport and planning my business trip to Guangzhou with an approved China Visa. My colleagues and I plan to travel to Hong Kong first and roam around. After that, we plan to take the bullet train to Guangzhou.

There is soo many "maybe" answers about what are the requirements to enter Hong Kong via flight from Kuala Lumpur; the requirements to enter from HK to Guangzhou via the HK border to China such as PCR test, and declaration form as such...

Please advise as detail as possible. Thank you!