As polish immigrant who moved to NYC as a kid and grew up here there's no place I love more than NYC but you're wrong about Warsaw. I've been to most major cities in the US and Europe and the standard of living in Warsaw is better than 95% of them.
I know that Warsaw is a great city, but I don't want to be a foreigner in Poland. I think there's a host of aspects that would impact the standard of living, when one is a foreigner in another country, that you aren't fully considering.
NYC is great because it's a city of foreigners. Warsaw isn't.
That’s the point why they are opening offices in Warsaw, they don’t want you to relocate there, they want to hire local engineers willing to work for like quarter of the US salary, and there’s no shortage of people like that there.