The goal of Prism OS is to provide developers working on embedded boards like Arduino, ESP8266, ESP32 etc with a platform that allows them to build apps and distribute them with ease, without the hassles of flashing, command line etc.
The advent of app stores have really simplified the way people install and try out apps today, and it has been the leading reason of success of smartphones amongst general consumers.
However with platforms like Arduino, there is no platform where people can release and distribute their applications.
Even worse, "installing" an application basically means connecting it physically to a computer and flashing onto it a completely new image, removing existing applications or data that may have been installed already.
Imagine if you could only have one app on your phone and you had to connect it to a computer to change to another app, cleaning out all the data in your phone!
Prism OS allows users to install apps onto their boards easily by just pressing "Install" on the app store and allows multiple apps to coexist together, all on a microcontroller board!