I like where you're going.
Thanks. I could accomplish voice announcements via the other BT interface and just push them as though they were music streams, but what I really want is for the announcements to come out in Alexa's voice. The ability to also issue commands this way is a bonus.
Assuming you don't need the remote, why not just hack the remote itself?
That's the easier, though messy way...and one already tried by a couple of other people. But what I'd like to do is not have to cannibalize the remote, and just do it all using a nice, neat little package like an Arduino or Raspberry Pi (most likely the Pi).
Can Echo pair with more than one remote?
No. At least, only one remote pairing is supported by the app settings.