Re: Leg Hypert Without Squats
In terms of work towards the strength aspect there is much strongman work without loading ther spine vertically that can be done.
Heavy sled work with the belt around the waist is also a great option – (and again here there is a continuum also to lighter/faster puls)
There is also hill work which I think is completely underrated.
So all those will develop strength-power
As far as plyometrics as Damian rightly said the most plyometric activity is in fact sprinting (which is why I often never see a need to do conventional plyometric bounding etc. with many players)