Hello,
I'm currently facing the same problem and I'm almost totally blocked.
I have tried to modify the base plugin usermedia without succes.
If we could make the choice for the camera with the base plugin it would be perfect.
That's what for the moment that I'm trying to following to help to create / modify something. https://simpl.info/getusermedia/sources/
Where in the source you can see that there's a "optional: [{sourceId: videoSource}]" added after user choice.
This sourceId is not even growing (1,2) but random...
Maybe if someone find this and could help (I'm still trying to do something but I'm poor js coder).
Regards