For a keyboard only user, there is no way to hide the volume slider once displayed.
The volume slider is displayed when the volume icon is mouseovered or focused and hidden only on mouseout (sort of), resulting it to be always visible if displayed for a keyboard only user.
Please refer the below animation.
I guess on blur of volumeSlider it should be hidden too.
Happy to raise a PR.
You may wanna check 3.x-dev branch. Some issues related to accessibility have been addressed there. Let me know if it works for you. We will release it soon
Can we keep the issue open till 3.x-dev is released?
Sure. No problem. I'll just label it as complete for now
3.0 version has been released.