Congratulations on your surgery! It's all progress from here. The other comment is right, just don't have anything directly, exclusively beneath your knee. You want that leg as straight as you can get it pretty much 24/7 at this stage.

I doubled up on pillows to help with my passive extension and bought the wedge, like you have, as well as this guy: https://www.amazon.com/ComfiLife-Orthopedic-Pillow-Sciatica-Pregnancy/dp/B01ARJ7SBM/ref=sr_1_1_sspa?dchild=1&keywords=knee+pillow&qid=1617206682&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzQVdTUk43OUNET0VVJmVuY3J5cHRlZElkPUEwMzQ0NTQwMUJVREpOQUpVUFQ0WCZlbmNyeXB0ZWRBZElkPUEwNDc4ODkyVUFET0NSU01WRjY1JndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

Double benefit of the elevation from the wedge, and then the gravity-induced extension from having your ankle in this cradle and the weight of your knee pulling it straight. It will be uncomfortable this early on in your recovery but that extension is so so so so worth it.