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Really small ESP32 PICO D4 module for 4.70 USD
Espressif released ESP32 PICO D4 before a few months. During this time, manufacturers released a few development boards with this WiFi and Bluetooth IC.
This news describes you really small module (smaller than ESP-WROOM-32) with ESP32 PICO D4, which you can buy on aliexpress.

Now, you can buy a few development boards with ESP32 PICO D4 - Espressif development board, Node32PICO or Maple ESP32 Mini. These dev boards contains USB connector, pin headers, buttons and LEDs.

This miniature module which you can easily buy and solder to your project was missing until now. Of course, ESP32 PICO D4 SIP is here, but you can't easily buy it.
TTGO Micro 32 WiFi Bluetooth module.

The board is smaller than ESP-WROOM-32 and the board contains ESP32 PICO D4 and also u.FL connector for external antenna. The board contains built-in ceramic antena.

Nothing more. Hence, the board is so small.

ESP32 PICO D4 is supported in Arduino IDE. The PICO version is the ESP32 but in different package.
The settings in Arduino IDE should be this. But I didn't try it.
Board: ESP32 dev Module
Flash Mode: QIO
Flash frequency: 80Mhz
Flash size: 4Mb(32Mb)
Upload speed: 921600 or 115200
Coredebug: none
Programmer: Parallel programmer

There isn't oficial pinout of this small module now :-(
The pinout which is showed below is NOT checked with hardware. If you have the board, please, double check the pinout of board!

The TTGO Micro-32 WiFi and Bluetooth module you can buy for 4.70 USD + shipping (in my case 2.31 USD).