How fighters could have disrupted the attack on Force Z

Could Brewster Buffalo fighters have protected Prince of Wales and Repulse?

Yes, if they broke up the unescorted Japanese strike; they did not need to destroy every attacking aircraft.

The Japanese strike was unescorted, so even limited fighter cover could have disrupted its coordination. Breaking a mass attack into isolated approaches would let shipboard anti-aircraft batteries engage one or two aircraft at a time instead of being overwhelmed from several directions. The Buffaloes did not need to remain in close cover or shoot down every bomber to change the result. Fleet fighter defence works by disrupting attack geometry so shipboard guns face manageable threats.