Not a bad investment as privacy is becoming more sought after now. However, for convenience it would be better to simply use an app on your phone rather than carry two devices around. Better to invest in Crypviser, product is almost ready and will be first to the market. Available now on bitshares and soon on hitbtc
https://ico.crypviser.net/yes, there are apps promising similar outcomes but apps depend on the OS so and on their bugs. As written in the website
"Regular mobile phone is vulnerable to attacks due to firmware holes and infamous mobile network threats. Avoiding mobile phones altogether is a reasonable strategy to uphold your sensitive data, person and freedom of speech. "