Now that you say, it is more likely to begin with ‘h’, because of it being prominent, I think it indeed begins with ‘h’, (with a ‘h’ silent and the word is happy instead of appy but since their flagship product contained apple juice, they reduced it to appy so that it goes with it). They came with a grape flavour which wasn’t as popular as the initial product and they advertised it with grappy (again trying to relate it with the juice type).
So, what you say is convincing (even because the letter ‘y’ in any typeset usually have curve in its downward part which the logo seems to lack and it looks entirely like h).
But I doubt that it is entirely because people at Appy overlooked this. Maybe it was a subtle attempt to engage people in conversations, as what should be the name? (Remember, no publicity is bad publicity) and we are falling right into that trap.