you dont need a device.. just the programming skills to make a good app for the current range of smart phones.
most people do not want to spend $20-$200 just to store there cash, but an app adds a layer of security to your phone.. that would work
Phone can get hacked, device can not. Would you prefer to use a phone as a cold storage device?
People have google authenticator app but they still use yubikeys.
I'd rather use a paper wallet for long-term and a hot wallet with just a few coins on my phone.