Weak right calf and ankle causing left knee pain

I had back surgery several years ago and there is damage to the S1 nerve weakening my right leg calf and ankle causing it to frequently invert (roll). I am 64 years old and I am an active hiker and walker.

As I walk I prefer the left leg and that has put significant pressure on my left knee. Five years ago I had meniscus tear surgery on my left knee. Still today after long walks or hikes, my left knee hurts and I have difficulty going up stairs without pain on my left knee following long hikes (10+ miles with 1,000+ ft elevation). Sometimes I feel my knee will give way. I also end up having plantar fasciitis on my left foot.

Can anyone recommend ways to strengthen the right leg without the nerve to have a more balanced walk? Also, a good recommendation on a mid-height hiking shoe/boot with good support for plantar fasciitis is greatly appreciated.