I am currently doing an RC car and I wanted to connect a PS4 controller by Bluetooth to my R4 wifi. However, the only videos I am finding on the topic relate to ESP32 (tried and libraries aren't supported) and none of the code examples from Sunfounder or Arduino show how to connect the Arduino to a specific MAC address.
The R4 just does BLE. I think the PS4 controller uses BlueTooth. They aren't quite the same thing.
Have a look at this thread. It's mostly about XboxOne controller, but there's some discussion about why the PS4 controller won't work with R4.