Public.com is an investment app that displays a set of plain vanilla assets: stocks and ETFs plus crypto. It expanded to offer fractional shares investments in high-performing stocks that could otherwise easily cost you thousands of dollars per share (look at Google or Amazon, for instance).Public.com is an investment app that displays a set of plain vanilla assets: stocks and ETFs plus crypto. It expanded to offer fractional shares investments in high-performing stocks that could otherwise easily cost you thousands of dollars per share (look at Google or Amazon, for instance).