There is a new FT8 APP for Android doing the rounds, called FT8CN from BG7YOZ (China). It is a free download and unrestricted in use. It is in the early stages of development, but is already up to version 0.86.
Download the APK file from here:https://github.com/N0BOY/FT8CN/releases
You will need to give your device permission to allow install of the APP.
There are various ways to configure the radio connection. The simplest VOX appears to use the Android device's internal mic and speaker.(Of course you could pipe the audio directly in and out via the audio socket on your Tablet or Phone). Direct CAT allows a USB connection, Bluetooth is available, and connection via a WiFi network. All these seem to be in early stages of development.
I soon got it installed, and enabled, decoding the audio using the internal mic of my Android tablet..
Split mode enabled showing Spectrum scope and received decodes.
It also plots the action to a live map via another quick tap on the screen.