Not bad, but you’re missing that the Bluetooth device can report audio latency back to the source so it can delay anything that needs to synchronize. In practice there’s half a dozen more buffers in between and a serious tradeoff between latency, noise sensitivity, and bandwidth.
Any cryptography you’re likely to encounter uses fixed size primes over a residue ring for performance reasons. These superlarge primes aren’t relevant for practical cryptography, they’re just fun.