I have the same opinion as @jcaron . MTU size is something that has to be configurable. We should be able to set MTU size of Pycom. Changing is not going to break anything in case of good implementation (I've already tried it with Pycom).
@Emmanuel-Florent the reason I've started this topic is that I've experience with ESP32-DevKitC and BLE MTU size changing, on that size everything worked fine, so I'm just requesting the same functionality on Pycom if possible.