Silicon Valley is a good place for you to go when you need to get in touch with other tech companies. But in order to find skilled developers you don't need to go to Silicon Valley at all. I'm living in Austria and I know that there are excellent developers right here (and I bet the same is true for Germany). You just have to know where to find them. And once you found them you need to start talking to them. I know its hard to tell total strangers about your big idea, but it needs to be done. You don't need to worry about someone stealing the idea as long as you and your expertise are still required. If the developer you told about the idea wanted to do it without you, he would face exactly the same problem as you do right now. He would need to find someone like you. And convince him of your idea. So why should he bother stealing the idea in the first place if he could just join you?
So, where do you find people that have a technical background and are also prepared to take some risks? Go to coworking spaces. That is where you find people that may be working as freelancers or in small teams up to 3 or 4 people (if the team gets bigger than that its often cheaper to rent an office for your own). But maybe you shouldn't just walk in there and distract people from their work. From time to time such coworking spaces host events. Usually they post about it somewhere on the web. And usually the people that work at the space go to such events. So this would be an ideal chance for you to talk to people that are both talented and not bound to a fixed job. My advice: Go there.
And now a suggestion concerning investors and money: Consider public funding. There are many funds that you don't have to pay back and in contrast to an investor the funding organizations don't ask for shares.