I use a Rearviz mirror strapped on my wrist.
https://www.rearviz.com/
I'd never be able to keep a mirror on my handlebars or helmet in one piece for long!
The Rearviz is pretty much infinitely adjustable. Change hands if you change from riding on the left to the right.
The disadvantage is that if you change your hand position, you can lose your rear view - but at the same time, an adjustment of your wrist means that you can see a lot more too.
It's finnicky in that it takes a while to get used to it, and to get the adjusting right, but it does do a reasonable job. Bear in mind I have no other mirror use to compare it to.
It can also be handy around camp to have a mirror. And it folds up when not in use so is reasonably robust.