Apple

Could any third party accessory be programmed to work as a wrist on detection? Yes, if the watchos was tweaked.

I would like to find a solution for wearing the apple watch Ultra in winter. Bulky clothing and an active outdoor job means the apple watch continuously loses the on wrist detection. I believe apple should sell some other method which could be unlocked with the phone, and would stay on under winter gloves. However, the Oura ring and others seem bulky anyway, so I may just deactivate wrist detection.