walking yoir cat on a leash is in fact the ONLY way to ethically enrich your cat outdoors. If a cat is the type who wants walkies - this is how you do it.
And further more, this shouldn't just be about cats. This is about fellow hikers, children, fragile folks with limited balnce, people with animal trauma, people with phobias, people with allergies, surrounding wildlife, and peace of mind.
If you don't keep your dog on a leash when interacting in the outside world (a place with limitless unknown and unseen variables) you should be prepared for the outcome you may inadvertently hurt someone or something, or deeply ruin their day. And if that doesn't bother you, please be prepared for the very real possibility that a person who sees a dog off its leash coming towards them may act in any number of ways out of self defense at its your fault - not theirs - if they do.
Control the environment of your domesticated friend.