There were Chinese Remnants at Mama Dolce

Very partially then.

IMO, it is very important for the tone/theme/lore that we would never actually know who launched the bombs, who pushed the button that ended the world as we know it.

(For many reasons stated in another thread)

About that, i think it would be quite interesting to have (not necessary chinese) a nation that have been spared by the great war, that got a incredible technological edge over the whole world in 200 years, have billions of people in their own country, and starts to invade the USA. They could represent a society that is not bad per se, but could be damaging for the wasteland, as unfortunate consequence. So, you could have to fight them, convince them to leave, or help them to ensure their invasion of USA.

I would like them to be some kind of lawfull neutral. For intance, they have pretty great laws, but use robot as law enforcer, that kill outlaws on sight, even if it is just a misunderstanding. For them, as they are billions, and were raised to follow these laws, it isn't a big deal, but once they come into the wasteland, they could destroy entire city just for one man's little mistake. Or maybe they are carrier of disease that kill regular wasteland quickly, with no way to cure them, as they aren't sick themselves. Or maybe they are dogmatic in some of their laws that don't make sense in the Wasteland USA. For instance, if they are billions, they may not allow couple to have more than a children. So they would kill all children bar one, in families that have more children, in the wasteland, which doesn't make sense in there, as they is an high death rate in the Wasteland. Other ideas like that...