Defrancos "Limber 11" is good as a diagnosis routine. Go through it once or twice and you'll def feel what's tight and needs to be worked on.
When I've had knee feels, the VMO has always been super tight, like it hurts to even touch it. That muscle just need a lot of smashing, either with hard ball or some kind of roller (one of those you use for baking work fine).
Also, when you do sumo pulls, it has looked like your knees are not far out over the knees as they "should" be. That indicates that your hips are tight and you need to be able to open them up. Frog stretch and rollback to splits are good for that.
For that posture, your hip flexor and quad are prob too tight from all the sitting. Sitting shortens the front of the hips and legs, so you need to lengthen them out by stretching. Do both stages of the couch stretch a lot. I did it 3x a day a year ago. Balance that out with strengthening the opposite side, which is glutes and hamstrings.