i don't have a pad or pod, just a lonely phone! the ocarina is best used on the phone because it has a microphone,
it can still be used on the pod though, but you don't get the benefit of vibrato among other. the same people make the leaf trombone, but imo it's meh; but he may like
it since he's a bonehead!!!
it's not something to jam with but i like music theory pro, no explanation should be needed!
as far as instruments to jam on, my next one will probably be hohner gcf mini squeezebox

it seems like to jam along with he may have it covered already.
there is a peterson tuner and i would imagine there are different score type apps as well.
nanostudio would be cool, but it's not for the pad yet and involves programming.
sorry if none of that helped!