Hi Bachus,
I had downloaded a couple of those apps , but haven’t really gotten round to using them.

I found a great online class, that I’m thoroughly enjoying, and ever so slowly working my way thru it.
They give you feedback too if one requires it.

Mainly Ballad, pop type music, and it’s great she teaches to play from a lead sheet or if one wants it a full piano arrangement, is available too for download.

The apps would probably be very interesting to kids.