Module can drive a maximum 8ohm load resistance if there is an embedded AB amplifier inside it. If there is no embedded AB amplifier in the module, then module can drive a maximum 32ohm load resistance. It is needed to add an external audio amplifier to drive 8ohm load resistance.
In my own experience, for example M66, without external amp will produce excellent handsfree speaker quality at good volume. Very important to experiment with echo cancelling parameters if using microphone as well.
All the best:
/Björn