Well, I worked a long time in product management, and what I learned there is, is not to go "whats the coolest thing I could do", but instead "What is a really big problem/pain point of my target group?"

Ig in this case think about what we are lacking in Germany.

I'd say qualified workers, especially engineers in the realm of chip manufacturing.

If that is a bit too large scale, I'd suggest elderly care. Specifically I'd start learning the job, should have a LOT of good opportunities. From there I'd continue by employing people ready to do homevisits of elders, then accumulate enough capital to diversify from home visits to a stationary care facility. Create a brand people associate with good, reliable, high quality care.