Watch

This is a list of carriers that support the Apple Watch, and the specific Apple Watch models support by those carriers. Make sure both China and India use the identical model.

https://www.apple.com/watch/cellular

Also be aware that some countries restrict which features are allowed on the Apple Watch. Make sure the feature(s) you want are support by the China Apple Watch if you decide to buy in China

https://www.apple.com/watchos/feature-availability

Finally, the warranty is country specific. You may need to return to China if you need to get warranty service, or just pay for whatever service you need out-of-your-own-pocket, if you do not want to take the Apple Watch back to China.