It doesn't say anywhere you need a free hand to load, so it should work for hand crossbows, or otherwise longbows cannot reload either (seeing how they're two-handed).
The 'loaded' requirement of the feat's extra attack is weird, but if the GM doesn't let you reload the hand crossbow as part of the attack action (like you could for regular bows), then, if nothing else, you can say you spend your 'free environmental interaction' of the turn on loading your crossbow, in order to get your bonus attack shot off.
