I have a balance board and an old handlebar that I sometimes use, though not as often as I thought I would. I’d also like to get a yoga ball though, probably soon.
I do a lot of slow speed practice on my bike though, and mtb/cx give endless opportunities to practice that - trackstands, slow speed turns, front/back wheel hops, side hops, etc. I do some skills coaching and encourage everyone I ride with to simply “play” on their bike every chance they get. Again, with mtb or cx, every stop or technical section is an opportunity, you can create those opportunities in a yard/park/driveway.
I wouldn’t feel embarrassed to ask this question at all, balance on a bike is something that just simply doesn’t come naturally to so so many people.