Absolutely. When I'm following a ketogenic meal plan, my baseline endurance shoots through the roof. I can walk/bike/whatever for hours. However, I do lose sprint performance.

As I'm in my 40s, and just exercise for fun and the health benefits, this is a tradeoff I'm more than happy to make. I'd much rather be able to cycle for another 10 miles without thinking about it than to increase my pace from 12 to 14 mph. But it is something to be aware of.

Anecdotally: yes. I've heard from some long distance runners that the ketogenic diet makes it easier to endure exercise. Your body runs on fat, so as long as you have stores then you can keep going until your muscles start to waste away. There is also anecdotally no "wall" that you need to break through, as this comes from exhausting your muscles' supplies of glycogen.

I've known many marathon runners that eat keto specifically because shifting to fat burning gave them incredible, and consistent, stamina.

On the other hard, weight lifters have complained that being keto has diminished their peak capacity. (They don't seem to care that it increases their stamina.)

It's almost outright recommended by people like Maffetone.