Just listen to what U.S. politicians say for their own country. Child tax credit, affordable housing, secure the border. Now look at what they suggest for China. They hope China repeats what many of them now regret. That being said I do think China could allow in more immigrants at a limited level if they are highly skilled and sponsored by an employer. It's not for mass immigration, but it's for a small amount of skilled immigration.
I don't think you can compare the 2 societies like that. One of the main reasons why US struggles so much with immigration is that they have low social trust. And despite their government acting like strongmen in the national level, on the local level, their control isn't that good. So it's easy for illegal immigrants to sneak in and create their own parallel societies.
China has a long experience already of inviting foreign labor to its coastal cities. The same issues have not happened.
The goal of immigration should not be replacing the local population, but making their jobs easier, so they can spend more time raising children. A limited number of economic migrants who prove skilled and integrated enough should be taken into society as citizens.
I am ultimately sort of an advocate for mass immigration in China, because I think the societal characteristics in China can contain any potential dangers.
