Mix coconut aminos, dry sherry, water, rice wine vinegar, sesame oil, ginger, and garlic together in a small bowl. Pour over chicken.
Cook chicken on High until tender, 2 1/2 to 3 hours.
Transfer chicken to a serving dish, reserving cooking liquid in the slow cooker. Cover chicken with aluminum foil to keep warm.
Stir bok choy into the cooking liquid in the slow cooker; cover and let stand until wilted, about 5 minutes. Transfer bok choy to the serving dish with the chicken. Spoon some of the cooking liquid on top. Discard remaining cooking liquid. Sprinkle sesame seeds over chicken and bok choy.