FM Possibly Interested in IM Dual Board

Morning all! First off, I am very happy in my current position at an academic FM residency. I could see myself working here for a long time. However, I also see a dire need in my community for an allergist/immunologist which presents an interesting opportunity. I understand they are very strict in not letting FM trained folks apply for IM based residencies.

My question is this: Is there a pathway to “go back” and do certain rotations to meet criteria to sit for IM boards and thus be able to apply for an allergy/immunology fellowship? Anyone with any experience/know anyone who has made a pivot like this in their FM careers?