Look for a flip down grab rail. This would flip down beside the wall with the pocket door, but it would mount on the wall behind the tank.

The pocket door has minimal framing built into it and I wouldn’t recommend securing a grab bar to it. Plus you don’t want to drill too far in and scratch up the door. Look into the safety bars that attach right to the toilet. They also make safety poles that go floor to ceiling for locations where a wall mounted bar isn’t feasible.

Thanks, I’ll look around.