I have
no medial meniscus in one of my knees, removed due to injury 40 years ago, so I have a fair amount if instability there, and the older I get, the more tender it becomes, making hurting it easier. As my ortho doc says, "you're down to polished bone on polished bone", and also said that if I want to continue windsurfing, I'd need better support. Over the years I've been using all sorts of knee braces, with some success, mostly neoprene sleeves worn under my wetsuit, but that doesn't seem to do the job like they used to. Then a friend of mine with a similar issue, turned me onto this new knee brace, and wow does it work much better, it's a great design w/o any cumbersome hardware.
For me it's working great, worn under my wetsuit, but my issue is different than yours, however, instability is instability, but not so much with this.
Here's a link to the brace, I'm not affiliated with them, just a consumer, it did take about a month for it to arrive, but after using it for a few months now, that wait seemed to go by pretty fast, and I'd do it all over again if I had to.
www.aliexpress.com/item/32821978362.html