Doesn't this mean that the user won't hear real incoming calls while previewing ringtones?  Hmm. If there is an incoming call, I guess teh attention screen comes to the foreground and would therefore have priority over this app, so its ringer sound would win out.  

But what about the alarm clock? Even though it opens its own notification window, for the alarm, I'm guessing its sound wouldn't play since alarms are lower priority than the ringer, right?

And wouldn't this mean that we wouldn't hear notifications of incoming text messages while choosing a ringer?  That seems like the sort of issue that would be escalated to an IOT release blocker by partners.

If I'm just mis-understanding the issue, then a comment explaining why this channel type is needed will suffice.

If I'm understanding but there is no other way to do it, then a comment with a link to a followup bug will be enough.

But ideally, you can acheive what you want with some lower priority channel.