I’m not sure what specifics you want. People comment all the time on here about different opportunities you can do in PM&R. I would check the forum as well.
You can open your own business with outpatient rehab services and outpatient clinic. Can hire some interventional spine and sports docs and be a comprehensive sports and spine and rehab center. Add some ortho docs, surgery suites etc. Lots of overhead and chance of failure. Lots of established competition. Search your market well.
You can do regenerative medicine. Offer injections for cash. You can do modalities, osteopathic manipulation, alternative med, etc. Can get ecsw therapy, laser therapy, etc.
Make a Botox clinic. Start a hospital. Get into SNF consults. Create a new inpatient rehab center. Create a hospital that integrates transitions between acute care, LTAC, IPR, SNF much better than we have currently. Write a book.