One of the same-sex couples is an American citizen and the other is not eligible for immigration.

It depends on luck. It seems that some people have done good things and bad things before, but it is estimated that only K 1 can do it, because same-sex marriage is not recognized in China, and even marriage is impossible if the citizen's residence recognizes same-sex marriage. What kind of marriage immigration to talk about depends on whether the immigration bureau can accept it. But if you have an American marriage certificate, the probability of passing it will be higher.