I have create two Git repositorys to teach myself how to use the classic Arduino IDE with Teensy and ESP32 microcontrollers. You may find that helpful in exploring Teensy/ESP32 and the Arduino IDE yourself. Here are the links to the respective repositories: Arduino IDE and Teensy 4.1, see https://gitlab.com/hzahnlei/how-to-teensy4.1-arduino I2S on ESP32, see https://gitlab.com/hzahnlei/how-to-esp32-arduino

I have create two Git repositorys to teach myself how to use I2S on Teensy and ESP32 microcontrollers. You may find that helpful in exploring I2S yourself. On both controllers I am using I2S microphones for audio in and an I2S amp for audio out. With the Teensy I am also demonstrating how it can be turned into a USB audio device.