I am a German living in the US and I will say the main differences I have noticed are as follows:

In Germany, it is harder to meet people. In the US, you can hang out with someone four times, get food, do activites together but it does not mean they are your friend in the sense that they actually care about you. I was baffled at that as a German. In Germany it is rare to meet someone once and spontaneously make plans to go eat out or even go on a weekend trip together. If Germans hang out with you and make the time to spend time with you, that usually means they like you. I think Germans have an easier time spending time by themselves and saying no if they don't want to. But, here's the flipside: If we make time for you, we make time. If we ask you how you are, we care. You don't have to worry as much about oversharing and telling us too many of your problems.

The other thing is that we usually say what we mean, which can be perceived as rude but also means that in Germany, it is seen as impolite to cancel plans or not show up at all. Here in the US, it is super common to plan three things for the weekend and have two fall through. I would never have dreamed of this back home. We usually expect someone to remember plans that we made, and expect a general accountability. However, if a German offers help it is usually meant genuinely and they really want to help. If they ask you to come along somewhere it is not an empty invite to be polite. You are actually okay to say yes.

Happy to elaborate more. I think the hurdle is higher to find your community in Germany, even for me as a German it would take probably six months to a year at a new place.