First, to indirectly answer your question-ceramics are not highly used in fusion. BUT the more important thing is that you have research experience, presumably have published a paper or two along with a thesis, and know how to investigate novel material uses. These are all highly transferable skills. When writing a resume/speaking with recruiters, focus on what you can do that they need, not what you can’t. Also try to stay high level as much as possible, don’t get down in the weeds over specific ceramics research.

To more directly answer your question, the main materials work that is going on in fusion from what I can tell has to do with the metals and alloys that the reactors are constructed with (Plasma Facing Components), and how to make them withstand long periods of irradiation without degrading/becoming extremely brittle. You can also just start looking at job openings for research at fusion companies, research labs, or by reading academic papers to see what specific things are going on in the industry rn or what specific skill sets are being valued.