Here’s a couple videos of what you can do with a balance ball with resistance bands.
The resistance bands on mine are too weak for me so I don’t use them.
When I first started using it, at the gym I’d set up beside a hand railing on one side of me and used a 5ft long barbell bar in the other hand…I was that unsteady 
At home I set it up beside the side or back of an armchair and held my broom in the other hand. Gradually I progressed to just needing the bar/broom, until eventually I could do without.
If you have extendable walking sticks, maybe they’d be just a good…they’d need to be extended to allow for the additional height of the ball.
I don’t know how we’d do that but we could sort something out in messaging…chat would be good but for our time differences