Connecting an analog joystick to the ESP32 is easy. You can just connect this device to the analog pins. The ESP32 has two ADC1 and ADC2 pins, with some channels. You can find the analog pins with their channels on the ESP32 in figure 3-5:
Figure 3-5: ADC pinout on ESP32
Some ADC2 pins are used for internal devices such as Wi-Fi. For the ESP-WROVER-KIT board, GPIO 0, 2, 4, and 15 cannot be used for ADC due to external connections for different purposes.