I have TOS and cervical dystonia.
I have exclusively used buckwheat hull pillows for at least two decades. I've found that they are an ideal way for me to get the support I need. You can bunch the pillow however you like to make it as high or low in places as you need. They are also customizeable in that most manufacturers offer various sizes, and if you or someone you know is handy with a sewing machine, you can buy a zippered pillowcase and make it the size you need.
I use two travel-size (they fit in exactly half a standard pillow case, which I just fold over) pillows. I sleep on my side with one of them under my head, and the other in front of me. That one is to keep me from rolling too far onto my stomach, as well as to provide support for my left arm (TOS arm) when it's particularly ouchy.
Here is an example of the type of pillows I am talking about.
Beans72 Organic Buckwheat Pillow - Travel/ Child Size (11 inches x 16 inches) https://www.amazon.com/dp/B000N90JPY/ref=cm_sw_r_cp_api_i_Zb1fFb93CE194