I would not trust suction cup grab bars. Too much is at stake if they should slip.
When I opened a thread about grab bars on TOTV I received a couple of suggestions. One was Grab Bar Bob, who advertised in The Daily Sun. I talked to him but did not feel his method of anchoring the grab bars to the plastic wall of the shower was adequate.
Another suggestion was Abshier Shelving & Mirror. They said they would not install grab bars in pre-fab plastic showers such as mine. They recommended
Mike Scott Plumbing.
Mike Scott Plumbing gave an estimate, with one stipulation. Their method is to cut out the wall behind the shower and install a sturdy 2"x4" stud to which they affix the grab bar. However, they do not repair the wall. You have to find someone else to repair the plaster wall, and touch up repaint.
I had them make an installation both in the shower and the bathtub. I had a friend who is a handyman repair the walls.
I use the grab bar in the shower and it is quite satisfactory in assisting me to pull my 250 pounds up to a standing position from a shower chair. Then I use a walker to step out of the shower and transfer to a wheelchair. It works well for me.
Best wishes on successful surgery and rehab.
Mike Scott Plumbing