As Underfire stated, WGS84 is a worldwide system adopted by ICAO around 1989.
In the early days of RNAV, but later than 1989, many countries were not WGS84 compliant. More and more complied as the years passed. Several years ago if I would select an airway or terminal procedure in a country that was not WGS84 compliant, I would get an advisory message "X Country not WGS84 Compliant."
I believe most countries are WGS84 compliant in 2017. I tested Russia at UUDD with a current database. UUDD has several RNAV approaches. I did not receive a WGS84 noncompliance advisory alert for a UUDD RNAV IAP that I selected.
As to China, Hong Kong has RNP AR procedures. So, at least that portion of China is WGS84 compliant. So is Tibet as it has a very sophisticated RNP AR approach procedure developed some years ago for China Airlines by Naverous.
I selected ZUCK in China that has some ILS procedures with RNAV transitions and some without. I wasn't able to select the RNAV/ILS procedures. I'm not sure what that means.