For example the popular arm rockchip offerings are so bad at contributing to mainline linux or even sharing documentation that the single person supporting them dropped it due to lack of fund and being unable to get any contact to share documentation.
IMHO, chinese opensource does at best the same thing many western companies do:
Opensource the things that are not you secret sauce/income, or things which would benefit you if people adopt them.
With the added caveat that china in generally is notorious for not abiding by patent laws and copying.