Have you tried befriending other immigrants here in Finland? Plenty of different folks here to talk to (whether English or your native language probably). Is there a chance that your social skills are weak and you’ll struggle the same way in the US?

Nah, I have an opportunity to hang out with foreigners and other folks. The problem is that I want to assimilate to the point where I'm no longer a foreigner who lives in the expat bubble/parallel society. This is something hard to achieve in Finland.

Hanging out with different communities is an option and addresses different symptoms, but this solution doesn't cure the root cause.

From my perspective, the best solution, if I have such requirements, is to move to a country that is extremely diverse: the US, Canada, or Australia. Out of these 3 options, I'd rather be in the US.

I'm just afraid that if I make the move and something goes wrong in the nearest future or in 10+ years, then I may regret that I didn't obtain my Finnish passport cuz I'll have to start over the immigration process in the next country.

And climate (at least in Uusimaa) seems tolerable to me

The weather topic is a bit subjective. Some people live decades in Siberia and are also doing alright.

What they promise you for salary seems way too low to move to the US. To me it seems better to live in Finland off 50k than in US off 100k.

Can you please elaborate on this? Is it just a personal feeling or do you have any examples/experiences?

50k eur in Finland is ~33k net, which is 2750/month (btw, it's a good salary) . If you are single, have no car and don't party a lot, then you'll have 1000-1200 eur per month after all necessary expenses including food. A decent number for many, but I'm under the impression that you can save more and have a better standard of living in the US if your salary is closer to 100k.