(I posted this on the vivoactive HR forum and was told to post it here instead.)
I just got a vivoactive HR for my birthday, and I've been enjoying it so far.
I was tempted to get a Fitbit Surge because its music control can control 3rd party apps, whereas vivoactive HR can't.
But the features provided by vivoactive HR outweigh this drawback, so I chose vivoactive HR.
The fact that the music control can only control the default iOS music player is baffling to me.
I have multiple Bluetooth headsets and speakers that can control 3rd party music apps on iOS, so this can definitely be done.
I am a software engineer myself, although not an expert in Bluetooth communication, but I believe this is just a matter of sending the correct commands through Bluetooth to the phone that would trigger the 3rd party apps' playback actions.
Looks like sending playback commands using the AVRCP profile would do the trick.
https://developer.bluetooth.org/TechnologyOverview/Pages/AVRCP.aspx
https://searchcode.com/codesearch/view/13977666
Please, Garmin, have some engineers look into it.
This is the only missing feature that would make my vivoactive HR perfect for me.