Something that has helped me tremendously is to care less about the opinion of the interviewer and the company. An engineer provides value through their skills

Something that has helped me tremendously is to care less about the opinion of the interviewer and the company. An engineer provides value through their skills and I'm there to present my value and offer it. If the interview process is dehumanizing or badly conducted, this is a signal about the company/department itself sharing the same characteristics. If I don't see bad intent, I also assume that the interviewer is trying to do their best for me to succeed. Their aim should be to get the most out of every candidate and not to pressure someone into failing. This may sound irrelevant to the fact that you are finding it hard to describe your achievements, but I think that the mood of the interview matters a lot. A positive mindset on your part can relieve a lot of the tension and with less tension, there's more bandwidth to think.