NGL, not asking for a friend. Given the current trends in US politics, it seems prudent to at least look into it.
Most of the online content on the topic seems to be by immigration attorneys hustling ultra rich people. I’m not ultra rich. I have a job in tech, could work remotely, also have enough assets to not desperately need money if the cost of living were low enough.
I am a native English speaker, fluent enough in Spanish to survive in a Spanish speaking country. I am old, male, cis, hetero, basically asexual at this point. I am outgoing, comfortable among strangers.
What’s good and bad about where you live? Would it be OK for a outsider, newcomer?
No, they are not. Seamless integrating yourself means to be able to communicate with your environment and to accept local laws and customs. I expect someone to immigrate from e.g. a Muslim country to accept that sharia is not our law, and that he has to accept that women are allowed to speak and gay people are not to beheaded.
On the other hand, I would not ask them to lose their cultural identity. There is no reason they cannot remain Muslim and observe their own religious customs or celebrate their holidays.