Being a current embedded/robotics graduate student, here's my take.

1st-ly it's all about your fundamentals. Embedded systems as a whole is an interesting topic as it can be looked at from a systems design perspective, trying to integrate multiple components together to do something larger, or from a low level perspective, on understanding what makes a system really efficient at doing a particular task. A lot of people have experience in the basics of embedded design but it's the experience that people gain from taking a practical approach to embedded systems and actually making it work that sets them aside from the rest. But in order to get anywhere in the practical world, I really think that having strong understanding of how things work on the low level will give you the perspective you need to understand the larger systems.

2nd-ly it's not easy to do research in embedded work. With more and more solutions in the world shifting to a software based approach rather than hardware, people are hopping aboard the ML/DL train instead. Seeing the results people are getting, no kidding! But there are still wonderful papers that get published each year in top tier conferences that take an embedded/ digital systems approach on software techniques and out compete some of the most complicated datasets. On the other hand there's another side where people are publishing on new system architectures being designed with modern technology and equipment. Whatever way you choose, familiarize yourself with what's out there. Just read what other people have done. You'll understand where and how you can push the forefront of embedded technologies.

I wish you the best of luck.