Here is the current version of the$16.95 ESP32 development board using an ESP-WROOM-32 module directly from Espressif. My optimism about the availability of the ESP32S modules from AI-Thinker was misplaced. I believe they are finally shipping now but since I haven’t seen any with my own eyes I remain unconvinced. In the meantime, I switched to a module that is actually available in production quantities.
The ESP32 board has a Espressif WROOM-32 module installed with the pinout marked on the PCB albeit in very small letters. The PCB is routed out under the antenna for the best RF performance. The WROOM-32 module is certified worldwide by the relevant authorities and has an FCC Id number.
http://www.ezsbc.com/index.php/products/wifi01-28.html is where you can buy some for $16.95 each. The schematic is also available for download and there are a few example programs on the forum.