I'm not the most experienced lifter on these forums, but I thought it would be interesting to have a thread where people can post useful information they think others might not know.
Your knees wanting to pull in on squats is a sign of weak adductors. I honestly don't remember where I heard this nnline, maybe someone can explain it? It seems counterintuitive, because the adductors are what pull the knees in, but ever since I started doing side lunges and adductor work my knees haven't pulled in nearly as much as I come out of the hole on squats.
Note: Glutes not firing can also cause the above problem.