Is there an option of streaming audio via bluetooth to mopidy

Not necessairly but it could be also done like here GitHub - lukasjapan/bt-speaker: A simple Bluetooth Speaker Daemon for the Raspberry Pi 3. The simpler approach would be to let the audio be handled Independently by some other software like bluez-alsa or pulseaudio because the audio is transmitted with different protocol (a2dp). Avrcp is only for control and metadata.