I moved from Boston metro (specifically Cambridge) to NYC and I have found it immensely easier to make friends in NYC. Like instantly easier, from day one.
I could point out a lot of reasons why I think NYC is an easier place to make friends, but truthfully I'm not sure how much of it is Bostonness and NYCness and how much of it is just that it suits me more and I'm happier here and I fit in better. I do more, I go out more, I see/meet a ton more people, there are way more opportunities to do interesting things that make it easy to talk to people. I found my 'tribe' here. I think moving could make a big difference for you, especially if you make an effort to change up any homebody habits you've gotten into.
There are absolutely people who wouldn't make friends anywhere, but you don't strike me as that type. (My dad, for example, who is also a scientist, seems to have quite a few work "nemeses," dislikes a number of his collaborators, frequently doesn't get along with his bosses in a major way, thinks people at his university are constantly screwing him over, etc. and talks about all of this constantly, which makes me think the problem is him... I think he's managed to make one very casual friend in the last 20 years, they play tennis sometimes.)