Hunting season isn’t open all year where I live. There is a period in the spring and early summer when it is illegal to run dogs in order to protect ground nesting birds. We spend a significant amount of this time hiking and packing.
Walking on a leash in the neighborhood isn’t as rewarding as running loose though the forest, so I often have my dogs carry packs to give them a job and ensure they get a good work out. We hike anywhere from 3-15 miles almost every day.
I keep my dogs leashed on hikes as it is often required, but also so they don’t jar their joints while carrying a pack, which can weigh anywhere from 5-11lbs. WSL will turn any activity into a hunt when they see, hear, or smell game they have been encouraged to hunt, which is another reason why I keep my dogs leashed on hikes.

I recommend Wolfpacks. They are very well made by a small company in the U.S.
Another good brand is Ruffwear. I have many of their packs and like the Singletrak best.