Hm, would the Ford Fellowship maybe be applicable? https://sites.nationalacademies.org/cs/groups/pgasite/documents/webpage/pga_362124.pdf
GRFP is annoying because results come back in April, far past when anyone would be still interviewing students, so I don't know how it would help unless you've been waitlisted. I also applied to it with the hopes of it boosting my (not-clinical) applications, before I realized the timelines wouldn't match up. It did come in handy however, forcing me to have a personal statement that could be adapted for grad apps, and a research statement that I used as a writing sample.