Ok - with a little help from this post: WebRTC - Does it work with the latest FreePBX? — FOP2 Forum I got it working - A couple of settings he lists are not necessary so I will post here the necessary settings so if anyone finds this post, they know how to get it working:
Set up a Standard PJSIP extension, but under Advanced:
He calls for rtcp Mux to be turned on - in my testing, that was not necessary.
He also calls Enable WebRTC defaults to be turned on - I haven’t found that needed either.
Without this, you get no audio whatsoever - not even one way in my config. Here is my question - why is this not recommended - I have been Googling and reading for an hour and nowhere can I get a definitive reason why this is showing as not recommended - Digium Folks?
Make sure you select your certificate below this and turn it on.
This makes the WebRTC phone in FOP2 work quite nicely - I am going to pair it up with a physical phone now and see if a phone works properly with this extension config.