An interviewer has asked for a copy of an unpublished manuscript I'm writing, is it safe to do this? The paper is one I'm working on as part of my current role for which I'm not the PI. Is it safe/sensible to share this with my interviewer? I don't have any published articles at present, so I assume they are just interested in seeing writing samples and such. Should I offer them a copy of my PhD thesis instead?

The interview was for a job in academia I am applying for.
There's no concrete, objective answer to this. My opinion is that it's fairly safe to give unpublished manuscripts to an academic interviewer. You definitely need specific permission from all the co-authors on the manuscript, though. If the interviewer is directly in the same field as you, and might be working on the same topic, you might be more hesitant, but it's not a definite "no".  Hopefully, if you're interviewing and considering working with this person, you've already decided that they are not a horrible human being, so you've already done a little of the due diligence.