Similarly is the squat a straight swap to a leg press? I've read Lyle's article on squats vs leg press so I presume it's kinda fine but am I missing much out in the transfer.
Figure a squat works lower back pretty hard and upper body to some degree. You're going to want to do it fresh, and it's more demanding on recovery. There's a greater degree of hip extension compared to most versions of leg press.
They're both compound quad movements though. They will both heavily recruit glutes and adductors.
So for aesthetic purposes, there's a lot of carryover, but it's still important to know where they differ.