Hi,
Would it be weird for me to send them a photo of me so that m interviewer can find me better in a cafe? The place we’re meeting is super busy so I feel like it would make things easier for both of us.
I think most interviewers wouldn’t feel it would be weird, but I think the safer thing (how most people, including interviewers) pre-identify themselves in a busy place is describing a distinctive article of clothing(s).
it’s actually easier to look for an article of clothing than a face. I’m an interviewer, and just tell them I’ll wear a sweatshirt of my alma mater 
Our son’s a happy Yale Junior and, like @donnaleighg, his interviewer when he was in your position told him to look for a guy in some sort of specific article of clothing (sweater). This also helped our son know to dress a bit more casually. Good luck with your interview, it was our son’s most enjoyable one, he viewed it as an opportunity to not only be interviewed, but also to ask questions and better understand Yale.