I am interested in creating my own altcoin that will be minable through a phone app.
If the coin will be mined with phone app, there's huge chance it will also be mined by any modern CPU and GPU. The difficulty will rise and phone mining will become worthless and get dropped.
So unless you have some ideas how to make your coin get mined ONLY by phones, your idea doesn't look so great to me. Unless you or somebody you team up with will find a solution for this, your idea doesn't worth the attention for an ICO.
Came to the conclusion that mining is not a good idea. Coins will be pre-mined and users are awarded coins for using the app.