I started doing endurance training about a year ago. Never had a big issue with knees but it was clear they were getting pounded and beat up. Having sprung back to other work outs too hard in previous years, I got a plan and stuck to it. It ramped up the mileage for weighted hikes and running miles somewhat slowly and built up that mileage. Initially I was running 3 or 4 miles at the beginning with creaky, painful or sore knees feeling like they were getting pounded, Now I can run 10 miles back to back days without too many issues other than they do feel like they are getting pounded sometimes.
Treadmill will take out some of the pounding as it absorbs more than flat ground does. Mix it in for added relief but understand there doesn’t seem to be a great replacement for working out on real elevation, hills or steeper.
Knees over toes guy on YouTube is making a living off of a focus on knees. One element from him I like is ‘dead mill’ - turn off the treadmill, use your own power to walk backwards on it for 10-15 mins a day. For me that’s something my knees seem to get a lot stronger doing and it’s very light impact, maybe give it a try. Could also just walk backwards without the treadmill for the same effect.
Lastly, your ligaments and tendons get stronger at a slower rate than your muscles. That’s why it takes time to develop them and can be frustrating as your muscle performance in strength and endurance ramps up but your joints feel rickety. A plan like Zap says is the way to go, and if getting focused on hunting, ramping it up slowly would be something to consider.