>Short of that, there is a wide spectrum on how countries treats immigrants. This is the most important factor for people actually living in a place.
Yes. Does China treat immigrants better than the US? As I explained, no. There is no contest. The comparison borders on the absurd. The US is a remarkably flawed country in many aspects, but the vast majority of the stigma around its immigration comes from the fact that it's a matter that the US takes very, very seriously. The bar for living somewhere is not necessarily citizenship but it absolutely is a factor if someone is seriously planning to immigrate somewhere.
For an incredibly evident and very current example, the 14th amendment was very recently reaffirmed, with a whole lot of people being horrified it was even thrown into question at all.
>How is getting money and support to live in a place not related to immigration?
Because any quantity of money beyond a livable wage has barely any relation to integrating people into a culture. A model of immigration based on money is not immigration at all, that's just hiring foreign workers.