Received the product. Haven't tested it yet and have no idea on how to proceed since this is a clone of the STM32F103C8T6 chipset. So the received product will have a CKS32F103C8T6 chipset and not the original STM32F series. Hoping that this would be compatible with the debugger and programming methodology used for STM's.
This CKS microcontroller is recognized as an STM32 (naughty) by STM32CubeProgrammer when connected with an ST-link. Programming a firmware compiled for STM32 seems to work (I haven't tested any advanced function but the LED is blinking and messages are displayed in the serial console). Also works with stm32duino core and Serasidis HID USB bootloader. Unlike some bluepills, the R10 pullup resistance for the USB D+ line is 1.5k which is the expected value. Strangely (or not), I own some bluepills with chips marked STM32 which look more like this chip than STM32s for which I am sure of the origin :) To conclude I bought this STM32 clone to test and ... for now it's not that bad.