Android P might remember the volume levels that were last used on connected Bluetooth devices.
The Android Open Source Project ‘Commit’ was first spotted by XDA Developers and it’s called ‘Implement Bluetooth device volume memory.’ The feature will make it so Android is able to remember the volume of previously connected Bluetooth devices.
Android Oreo currently connects Bluetooth devices at the same volume, regardless of whether the device is a pair of headphones or a speaker.
The feature hasn’t officially been pushed out, but the fact that it’s reportedly being worked on indicates that it could soon be officially released.
For users looking for this functionality now though, there’s an app called Bluetooth Volume Control that accomplishes the same thing.
Update 18/04/18: The ‘Implement Bluetooth device volume memory’ commit has been merged. Which makes it seem a little more likely that this feature is going to appear in the second developer preview of Android P.