I remember once I worked at a company that was being acquired by another. As part of the screening we all had to go over to the other company to do an algorithms interview. Everyone - including my boss. Our company had a pretty softball interview process and most of our engineers hadn't been through a real gauntlet before.
I knew what to expect, had practiced these things, and made it through. I tried to warn my colleagues that they were in for something a lot more difficult than what they were expecting. But yeah, as you might expect, almost everyone failed.
I remember my boss talking about it, shaking his head slightly, his mouth screwing up into that familiar chagrined smirk so many people get after performing poorly at these things. I told him that these technical interviews are purposely difficult, that most people fail. That it's much better for them to miss a good candidate than hire a bad one. That failing is normal. I could see some of the tension in him subside after I said that. I repeated, "It's normal." He calmed down some more. The word "normal" seemed to help a lot.
I wonder if bringing in elements from psychotherapy might help a surprising amount here. I've found that software engineers highly value rational thought - to a point that they neglect the emotional side of things. A little development of their softer side can go a long way.
Like having a pre and post interview counseling session with a therapist would maybe be a little absurd. But maybe something along those lines would work. Maybe GPT4 could do it.