The feat reads: "You alter your appearance to blend in to the wilderness. In natural terrain, you can Sneak even if you’re observed."
Sneaking when someone is looking right at you is cool. But the sneak action says "You don’t get to roll against a creature if, at the end of your movement, you neither are concealed from it nor have cover or greater cover against it. You automatically become observed by such a creature."
So does this feat let me start a sneak while observed, but still require me to find cover or concealment by the end of my movement? So mostly just saving me an action for Hide?
Or does it let me become unobserved even without cover or concealment just by sneaking?
I think it's supposed to mean if you would be otherwise observed.
But as written it looks like you can just use stealth against a creature observing you, which if your stealth roll were successful would allow you to become unobserved.
I'm inclined to think you can end a Sneak without cover or concealment and still be unobserved, because Legendary Sneak kind of explicitly needs it to work that way to Hide without cover or concealment. They are different feats and all, so I'm not totally sure.
The generous interpretation means a Ranger can basically replace any Stride with a Sneak, which is a cool tool but probably not overpowered.