Nah, it's not as simple as you describe. Even if you download the actual official wallet and verify PGP signature and keep your mobile from installing multiple apps still you are exposed to internet, as long as the device is connected to internet you are prone to hacks in one or another way. Which is why the recommended way to store crypto assets, is cold storage it can be a device or hardware wallet but should be isolated from internet forever, the moment it connect to internet the security could be compromised.