Side Sleeper Pillow with Arm Hole, Shredded Foam Shoulder Pillow for Neck & Shoulder Pain Relief, Multi-Angle Armholes for Different Sleeping Positions, Ergonomic Arm Holes Positioner. 【No Pressure on Arms】If you are a side sleeper, the weight of your body is concentrated on your arms.
MedCline's Shoulder Relief System provides head and neck support designed for shoulder pain relief. Arm pocket and gel-cooling foam. Click here to buy now!
They are also sold at Walmart!
https://www.walmart.com/ip/Better-Sleep-Pillow-Fiber-Fill-Pillow-Sleeping-w-Arm-Under-Pillow/770557818
Try eBay!
You can get one here!
https://medcline.com/products/shoulder-relief-pillow
It’s already been invented.
https://www.khou.com/article/news/someone-invented-a-pillow-that-saves-your-arm-from-going-numb-while-spooning/285-da2ad580-cdfe-45e4-ac8e-68e16b1a84c0