To be clear, I think the overwhelming majority of jobs in the US fall into your uninteresting category, e.g. banking, adtech, etc.

There's a handful of places in the USA with thriving tech industry, and there's plenty of opportunity in general, but quite often people have to relocate for the really exciting opportunities. I haven't been to Spain, but my understanding of European culture is that folk generally stick around where they grew up. There's plenty of cool embedded stuff going on in Europe if you look for it. For example, I am aware of a lot of really neat drive-by-wire actuator development.

I feel you, unfortunately, your location matters in terms of your network/opportunities and even a spouse. Frankly, because I realized this I started searching for cool companies to work for that nobody knows and made a side project around this!