The chinese are mostly adding skins on top, not developing the core of the operating system.
There is however a chinese fork of android (state sponsored), but it has not gotten wide market adoption in china either to my knowledge, but i dont live in china so i'm open to be corrected.
Finally, even if that OS has gotten widely adopted in china - it IS a fork. the changes are not being upstreamed to android, hence irrelevant to the discussion on this forum.
The biggest Android market (internationally) are Chinese phones. If Google suddenly decided Play Store should be the only way to install apps, that doesn't affect Huawei and Xiaomi phones at all, they don't ship with Play Store and Play Services in the first place.
This isn't even a China-exclusive strategy, Samsung does the same with their Galaxy Store.
There must be a reason why Aurora Store is being advertised, though. Why would they do that if they could just pre-install Google Play Store and standard Google applications.
Update: End of 2018, I bought a Huawei phone with GApps. I remember that two or three generations later, Huawei was not allowed to include GApps anymore.
Chinese telephones legally imported usually have them in most relevant big markets like Indonesia, India, Brazil, etc.
The reason they probably have them preinstalled over there is because they don't care about licensing so they can freely preload whatever they want. At least that's how it was with netbooks in the early 2000s that they were selling loaded with MS Office, Windows, even Adobe, of course with no COA stickers.
This is why with Pixel they're focusing on competing with the iPhone, they want people to use Android so there is no point in competing with other Android manufacturer.