[lozenge]

Nope, for latency and battery reasons this would be done by a specific chip, e.g. https://www.icstation.com/audio-module-bluetooth-compatible-... / https://www.tinyosshop.com/ts8670

The same's true on the smartphone transmitter side.

[rstat1]

That 2nd link you shared, has 3 links under "Documentation" to firmware downloads.