I bought my mom a rollator (2 actually, one for inside and one for outside) and doubt they can go into overhead - and I would be upset if another passenger tried to stick it up there. Its too bulky/takes up too much space, Im sure it weighs more than what a pax is suppose to put in the overhead and youre suppose to lift/store overhead luggage yourself. I doubt it will fit in an aisle.
What about using airport services to get you around the airport and in/out of the plane?
Good luck on your recovery.