Similarities/differences/Interfacing between ESP32 and RaspberryPi
The ESP32 loads its code from a serial flash. This is either part of the modules you can buy or is part of the ESP32 chip - depends on the actual ESP32 module/chip as there's a few to choose from. As for an 'OS' - We're comparing a full blown Linux system vs a small embedded system. The ESP32 does not run on OS like Linux - more like FreeRTOS. There really is no direct comparison as there represent both ends of the spectrum.

Again the ESP32 is not running full blown OS like Linux. How do you interact with it? You have to add that code. It could be via the uart, WiFi, Bluetooth, switches and leds, lcd or nothing. That is up to you to decide. Out of the box, all the ESP32 knows how to do is load the code from the flash chip. What happens next is in the code you give it.

Whatever file format or data formatting is up to the code you provide.


With the ESP32, you'd probably start with the Arduino tools to get going. There's a zillion examples on the web for doing just about anything you can think of and is possible using the ESP32. There are plenty of libraries to do what you need. If you want to interact with it in a higher level - there's projects like Espruino that give you a javascript interpreter, Micropython gives you a cut-down python environment and so on.