Of course you can use a hardware wallet in combination with an Android smartphone, so it’s already something that’s been around for years, whether it is a wired connection or wirelessly via Bluetooth. While some will say that it may not be wise to show such a device in public, I don't see anything wrong with it if it doesn't store a large number of coins.

The security thus achieved is far greater than any other mobile wallet, but the question is whether we need it at all if mobile crypto wallets should only be for handling relatively small amounts?