Hamstrings?
Squats get minimal hamstring activation relative to working your quads.
You want hamstrings? And glutes and a great lower back?
Romanian Deadlifts. Now, before you get scared off, I’m not taking about full deadlifts.
Here are the RDLs. You can go very light, heck start with no weight at all. But this will give you what you want. Posterior chain strength and a spring in your step.
Of course, check with your doc first, please before you try ; )
Notice, your rear end moves back and hands stay close to your legs, just go down to the knee/just below knee.