According to this Reddit Experiment
https://www.reddit.com/r/Electroneum/comments/7j73su/mobile_miner_hashrate_experiment/Even the Snapdragon 835, which can be considered a high end mobile CPU only managed to get 20h/s
That is really slow, there's no way you could profit from it, not even mining Altcoins like Monero or Ethereum.
Forget about creating mining app, unless phone manufacturer decided to make phone solely for Mining

It isn't viable to mine from Android but it's quite a nice app nonetheless.
Also, there might be a way to connect a USB asic to a rooted tablet to get it to mine but it'll probably overheat or damage RAM due to the intense process needed.
I actually once tried to mine through phone, it got so hot that my phone overheats and shut itself off, the battery got bloated due to heat and I had to replace it.
Not a fun experience nonetheless.