This smartplug type uses a CDTech (China Dragon Technology) CDT-N582660-00 802.11 b/g/n wifi module. Specifications PDF here.
In addition to HTTP for cloud server control, it does also support TCP, UDP, & FTP. Firmware can be updated either through the physical UART interface on the module itself, or via cloud server.
Although this module seems to be derived from the ESP8266, it’s not identical. You’ll find many references to the ESP8266 being used with Arduino-based IoT projects here on the ST Community Forums, but there’s one thread dedicated to burning custom firmware to SmartLife H801 RGBW strip controllers to convert them from being cloud server-controlled to local-network controlled, and directly accessible by a ST hub through a combination of a custom device handler, SmartApp, and service manager written by @erocm1231. This firmware also works on certain Arilux RGB/RGBW LED strip wifi controllers, which use the ESP8266 module.
The big issue with using a similar custom firmware solution to give direct SmartThings control of these CDT-N582660-00 module-based smart plugs is that you will land up destroying the plastic case in order to gain physical access to the UART programming interface. So we’re left with the method of updating the firmware over HTTP, and you’d need to know how the company that made the TuyaSmart iOS/Android app has designed the method for firmware updates.
As much as I’d love to stop using the TuyaSmart app to control the two of these smart plugs that I have, there is basically no information on the web regarding how the CDT-N582660-00 is programmed to connect to their servers for cloud control, let alone firmware updates.
If anyone has found any information about hacking the CDT-N582660-00 wifi module, I’d love to hear it, so perhaps a similar method to @erocm1231’s could be created to release these smart plugs from 3rd party cloud control.