I struggle to believe that Bluetooth 5, which supposedly allows for a total of 2mbit/s transfer can't allow for a better codec to be used when a stereo stream of SBC is about 300kb/s. However, I'll be the first to admit that bluetooth is not my area of expertise, and my statement here is mostly driven by disbelief about the fact that we can't get better audio quality out of a bluetooth headset these days.

EDIT: Oh wait, the reason HSP uses low bandwidth codecs is because the standard makes a trade-off in favor of latency and non-blocking comms. Clearly, there are good reasons.