Native wearable application launch custom service by app_control_send_launch_request() call, and that works fine on Tizen 2.3.2 devices (Gear S2/S3). But service don't start on Gear Sport with Tizen 3.0: app_control_send_launch_request() returns APP_CONTROL_ERROR_LAUNCH_REJECTED error code. What could be the issue?
Try packaging service app with that wearable app from which you're trying to launch. I think it'll work.
You may go through Remarks section of app_control_send_launch_request() function in this link to know in detail.