FWIW, there are walkers for tall people. My dad (who needed one at the end) was about 6'4" (shrunk down from quite a bit taller- big guy) and they found one for him. No luck on one of the wheeled ones for him, though. The wheeled one he had had brakes - but they were only on when the handle was squeezed, which seemed backwards to me - people with non-wheeled walkers grab them to move them forward. No reason there couldn't be a brake-release-lever grabbed at the same time. It did scoot out from under him a couple of times (I got pretty good at butterfly closure thanks to it).

None of this would work on stairs or very rough ground (the one with wheels was OK-ish on his gravel driveway).

I'd also mention that I've had experience with using a walker at a rehab center. Having progressed to the point of not needing it was a major step (there should'a been champagne :-) )