Android already offers users separate volume controls for media, notifications, and alarms. Now, it looks like Google plans on adding another new addition to this -- the ability to independently control the volume of Google Assistant.
This would be a handy addition as it would ensure that Google Assistant can reply back to you at max volume despite the media volume being low or vice versa. As of now, the Google Assistant volume level is linked to the media volume of a device. Perhaps Google should allow users to control the Assistant volume level on other Google Home devices using this option as well as that would make it more useful.
The feature has been discovered in AOSP and the comment makes it clear that Google intends to offer a separate volume stream for other assistants like Bixby as well.
Add audio stream and usage for virtual assistant
New stream type: AUDIO_STREAM_ASSISTANT
This is intended to be used by a virtual assistant like Google Assistant, Bixby, etc.
The audio stream has own volume alias and the volume does not change by volume changes of other streams.
The feature is a part of AOSP but not Android 11 but could make its way to the OS with the next feature drop.
Source: Mishaal Rahman (Twitter)