if you have a phone, you have Chromecast or Airplay.. No need for any apps or anything..
Play radio or any other kind of music on your phone, and activate chromecast/airplay for output to your AVR, and the sound will be played by the Pioneer.
No need for a TV, Dirac, nothing.. (my Tv doesn't even get switched on when I stream music to my AVR..)
If you cannot be bothered by that, try internet radio directly on the AVR. (yes, it has internet radio included.. even DAB depending on region)
You spent a lot of money on a device that can do a lot. You bemoan having spent many hours for troubleshooting.. But I am feeling like you didn't shoot the trouble with a plan...
eARC shouldn't have anything to do with this, unless you connect the Blu-Ray Player to your TV and not your AVR..

eARC doesn't send any commands..
ARC means "Audio return channel".. and all it does is allocate a few wires on the hdmi cable to send audio from the TV to the AV-Receiver, so that the Tv sound can be played over your surround system, too.
eARC is the 2nd edition of ARC, allowing for lossless surround audio being sent via the hdmi cable..
Always connect everything to the AVR, and only one hdmi cable goes from the AVR to the Tv. (if you run Prime on your Tv, then eARC will be fine to transfer the lackluster Amazon prime surround audio to the AVR, but that's all it does..)
And I would definitely recommend running Dirac Live!
It's a 300 dollar software package you got for free with your AVR, and it's so simple to setup that a child can do it.
It will blow you away by how much it can improve how your movies sound.