For sale is a ESP32 C3 super mini ESP32 based microcontroller dev board. this is an ultra compact little board with a similar appeal point to compact controllers like the attiny, although this little powerhouse is a high powered, albeit single core, 32bit ESP32. all the pins like most ESP32s have significant ability to be remapped for alternate functions.
Personally this is my new favourite board, in the listing photo you can see a custom PID controller and interface all running entirely off a single well utilized C3 mini. almost anything you can do with a nodemcu esp8266 you can do on one of these as well, due to the complete lack of dead or single function pins. 5v rail is accessible too for powering 5v peripherals which most esp32s seem to be lacking.
This model for sale is specifically the model that is supported fully by the arduino framework, the C6C8.
Important note: this model has a poorly documented flash mode that lots of people get stuck on. in order to program the board, the "boot" button must be held down while the board powers up/ is reset via reset button. then the board can be programmed normally.