Luckily there are many types of compact exercise machines which specialize in non-impact and low-impact exercise, like exercise bikes, cross trainers, gliders, and even small floor standing
pedal devices where you sit in your own chair and pedal with your feet like on a bike, all far better that walking, and all adjustable so you can find a resistance level on the machine so you can do exercise that improves fitness rather than overworking you. These should be better for you, and your joints.