The duration of how long a command key is pressed / held (hold_secs) currently can only be globally configured for the remote harmony hub platform.
In general you want hold_secs to be 0. However, if you want to set a specific baseline volume for a device using the harmony hub, it is impracticable with a hold_secs of zero, since for many AV receivers it will then take a very long time (num_repeats would have to be in my case 140 and 50, even if delay_secs is set to 0.0!) to first reduce the volume completely and then to ramp it up until the baseline volume is reached.
For this use case it would be really beneficial to be able to hold the VolumeUp and VolumeDown commands for some seconds, because the device (e.g. AV receiver) will then automatically accelerate the speed with which it is reducing/increasing the volume.
It would be great if this can be implemented! I am not sure if the message format of the harmony hub supports changing the hold_secs before or while executing a command (if necessary, HA could automatically set it back to the previous value after send_command).
Could someone please check, if this could be implemented?
And if it may but put on the roadmap.
Thanks!