Edit2: Use the QR code on back of the PCB for a direct link to the source. The page is in Russian but the github logo will dump you where you need to go. All of this said I would not undertake this as a first time project if you have never messed with Arduino or any ESP32 stuff.
Edit: I was able to get this up and running the code was in the github under "examples". Had to figure out the board model and program it. Guess it's for the better because I translated the Russian user interface static elements into English before I uploaded. мкр/ч to µR/hr etc.
===== Old review =======
QR code links to a website with instructions strictly in Russian not English. Google translate worked alright there. Assembly was pretty quick and easy, however the "Wesmos Mini" esp32 looking clone appears to have no code on it. The GM tube board flickers, the battery charger board seems to work right.
So I went off to other projects created by this company and found a github to see if I could load the code needed to make this project work- to date I have been unable to find source for this device. I refuse to join a telegram group to ask why this is broken since this data should be on the github, and the github should contain instructions in english, and the github should be linked here. (If English instructions are not something you have that is okay, just, you should call that out in the product listing.)
I simply inserted CTC-5 tube that I already had, connected RadSens board to Wemos D1 Mini ESP32 with provided wires, created a simple sketch using RadSens1v2 library, uploaded it - and it all works and shows radiation level close to GMC-300E Plus device.
However I found RadSensBoard library easier to use (link below), and it also does not have some problems that RadSens1v2 library has - like writing 21 bytes to 19 bytes buffer.
There is also a MicroPython library for Raspberry Pi Pico: