Like this for example:

https://www.amazon.com/Angle-Back-Support-Systems-Immediately/dp/B009SYIGEG/ref=sr_1_1_sspa?dchild=1&keywords=under+knee+wedge&qid=1619322557&sr=8-1-spons&psc=1&smid=A3NNSMGVWETA6T&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExV0gxNkZUTTNLNUk3JmVuY3J5cHRlZElkPUEwODIwMzMwM0g2MEdKUFRVOEhXRyZlbmNyeXB0ZWRBZElkPUEwMTk3NDU1MU44MDg4RENRNjZDUiZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

Worth it or not worth it? There's the option to get multiple pillows but its shape might be a bit rounded