As engineers, we solve problems. Picking a problem domain close to your heart that intersects with your skills will likely be valued - and valuable. Engage the work, aim to understand and solve the human problems for those around you, and the way forward becomes clearer. Human problems (food, health, safety) are generally constant while tools may change. Learn and use whatever tools to help you, be it scientific principles, hammers or LLMs. For me, doing so and living within my means has been intrinsically satisfying. Not terribly successful materially but has been a good life so far. Good luck.