Call isInternalStorageSupported will know it the aircraft support interal storage. If returns True, then you call call setStorageStateCallBack to add a listener for storage state. The return will occur for every 10ms. One is internal storage state and ther other one is SD card storage state.
You can call getStorageLocation to know the current callback is either internal or SD card, then call isInserted to know if an SD card has inserted.