Dynamic choice/usage/change of audio/video devices

**Feature request**
When joining a call or already in a call, I would like to be able to:
* join the call without any devices (no permission given to the browser or no device on my computer): I'm only a listener
* join the call with only 1 type of device (microphone or webcam only):
* I don't have webcam on my computer (cases where professional laptop are required to have no webcam)
* I don't need to have sound (too noisy in the factory I'm walking in), I need to walk around and show the problematic machine to the support (on the other side of the call)
* be able to switch on or off my permissions (this is not the mute feature I'm referring to) of sharing the device during the call
* I might join a listener, then would like to participate (but audio only, or video only)
* be able to force via the webpage to re-request permissions to access devices

**Describe the solution I don't like** ;-)
Here is a capture of this morning's view of the call.element.io I have. I can't join the call in this state.

**Describe the solution would like**
More buttons to be able to manually re-trigger the permission request.

Or be able to join the call in this state (right now it's not letting me).

**Additional context**
Permission/state switching:

Having more states/actions based on the type of conference call we are in:
* you've been muted by x
* you're not allowed to share voice/video
* raise hand to share voice/video

**Current context (just in case)**
* Ubuntu 20.04
* Firefox 98 in private mode with some ad blocking extensions
* If permission to request webcam is enabled (browser config) the element call request never reaches the user to permit device usage
* Generic usb microphone
* Generic usb webcam