Does RC override even work?

I have made software to control a gimbal (for marker tracking) on my quadcopter using channels aux1 and aux2. I just need to be able have this software set the pwm signal on those pins. In ArduPilot this was no issue because I could use both manual control and RC override to switch between manual and automatic control as I wanted.

In PX4 this seems impossible and it is very frustrating to read countless unanswered posts on this topic.

I have tried pymavlink’s mav.rc_channels_override_send, dronekit’s command_long_encode with MAV_CMD_DO_SET_SERVO, and MAVROS’ override RC in topic. Nothing works, and no usable error messages are output.

Is there any way to make it work, or is it completely broken/unusable?

Additionally, is there any other way of automatically controlling a device via PWM? That is my main goal.