I want to know is there a way we can program a Bluetooth dongle (NRF dongle, esp32 or even raspberry pi) to work as a Bluetooth adapter for PS, Xbox or Nintendo controllers. I found one product called 8bitdo. Very interesting product, it can connect between different controllers and platforms. Its like an universal adapter. I want to know is there any open source code available for this project. I'm new to embedded engineering. So, excuse me if I sound silly. But I'm curious about this project. If someone can tell me where to start, or give me some idea on how to do it, it will be helpful. Thank you.
Take a look here for Dualshock 4 (PS4) Controllers. Here's an already existing project using an ESP32 for a Dualshock3 (PS3) Controller.
But please use google next time, this took me only 1 minute to find.